Merging upstream version 125.0.1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

56 files changed, 695 insertions, 919 deletions

diff --git a/toolkit/mozapps/defaultagent/BackgroundTask_defaultagent.sys.mjs b/toolkit/mozapps/defaultagent/BackgroundTask_defaultagent.sys.mjs
index c727a55997..691f76c319 100644
--- a/toolkit/mozapps/defaultagent/BackgroundTask_defaultagent.sys.mjs
+++ b/toolkit/mozapps/defaultagent/BackgroundTask_defaultagent.sys.mjs
@@ -17,8 +17,6 @@ const EXIT_CODE = {
 const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
   setTimeout: "resource://gre/modules/Timer.sys.mjs",
-  BackgroundTasksUtils: "resource://gre/modules/BackgroundTasksUtils.sys.mjs",
-  NimbusFeatures: "resource://nimbus/ExperimentAPI.sys.mjs",
   // eslint-disable-next-line mozilla/no-browser-refs-in-toolkit
   ShellService: "resource:///modules/ShellService.sys.mjs",
 });
@@ -37,11 +35,20 @@ ChromeUtils.defineLazyGetter(lazy, "log", () => {
   return new ConsoleAPI(consoleOptions);
 });
 
-// Should be slightly longer than NOTIFICATION_WAIT_TIMEOUT_MS in
-// Notification.cpp (divided by 1000 to convert millseconds to seconds) to not
-// cause race between timeouts. Currently 12 hours + 5 additional minutes.
-export const backgroundTaskTimeoutSec = 12 * 60 * 60 + 60 * 5;
-const kNotificationTimeoutMs = 12 * 60 * 60 * 1000;
+// Should be slightly longer than kNotificationTimeoutMs and kGleanSendWait below
+// (divided by 1000 to convert millseconds to seconds) to not cause race
+// between timeouts.
+//
+// Additionally, should be less than the Windows Scheduled Task timeout
+// execTimeLimitBStr in ScheduledTask.cpp.
+//
+// Current bounds are 11 hours 55 minutes 10 seconds and 12 hours 5 minutes.
+export const backgroundTaskTimeoutSec = 12 * 60 * 60;
+
+// 11 hours 55 minutes in milliseconds.
+const kNotificationTimeoutMs = 11 * 60 * 60 * 1000 + 55 * 60 * 1000;
+// 10 seconds in milliseconds.
+const kGleanSendWait = 10000;
 
 const kNotificationShown = Object.freeze({
   notShown: "not-shown",
@@ -148,25 +155,11 @@ export async function runBackgroundTask(commandLine) {
 
       lazy.log.info(`Running do-task with AUMID "${aumid}"`);
 
-      let cppFallback = false;
       try {
-        await lazy.BackgroundTasksUtils.enableNimbus(commandLine);
-        cppFallback =
-          lazy.NimbusFeatures.defaultAgent.getVariable("cppFallback");
-      } catch (e) {
-        lazy.log.error(`Error enabling nimbus: ${e}`);
-      }
-
-      try {
-        if (!cppFallback) {
-          lazy.log.info("Running JS do-task.");
-          await runWithRegistryLocked(async () => {
-            await doTask(defaultAgent, force);
-          });
-        } else {
-          lazy.log.info("Running C++ do-task.");
-          defaultAgent.doTask(aumid, force);
-        }
+        lazy.log.info("Running JS do-task.");
+        await runWithRegistryLocked(async () => {
+          await doTask(defaultAgent, force);
+        });
       } catch (e) {
         if (e.message) {
           lazy.log.error(e.message);
@@ -181,7 +174,7 @@ export async function runBackgroundTask(commandLine) {
 
       // Bug 1857333: We wait for arbitrary time for Glean to submit telemetry.
       lazy.log.info("Pinged glean, waiting for submission.");
-      await new Promise(resolve => lazy.setTimeout(resolve, 5000));
+      await new Promise(resolve => lazy.setTimeout(resolve, kGleanSendWait));
 
       return EXIT_CODE.SUCCESS;
     }
diff --git a/toolkit/mozapps/defaultagent/DefaultAgent.cpp b/toolkit/mozapps/defaultagent/DefaultAgent.cpp
index 2ebb5e466e..3bff6e3243 100644
--- a/toolkit/mozapps/defaultagent/DefaultAgent.cpp
+++ b/toolkit/mozapps/defaultagent/DefaultAgent.cpp
@@ -7,11 +7,8 @@
 #include <windows.h>
 #include <shlwapi.h>
 #include <objbase.h>
-#include <string.h>
-#include <vector>
 
 #include "nsAutoRef.h"
-#include "nsDebug.h"
 #include "nsProxyRelease.h"
 #include "nsWindowsHelpers.h"
 #include "nsString.h"
@@ -304,62 +301,6 @@ DefaultAgent::Uninstall(const nsAString& aUniqueToken) {
 }
 
 NS_IMETHODIMP
-DefaultAgent::DoTask(const nsAString& aUniqueToken, const bool aForce) {
-  // Acquire() has a short timeout. Since this runs in the background, we
-  // could use a longer timeout in this situation. However, if another
-  // installation's agent is already running, it will update CurrentDefault,
-  // possibly send a ping, and possibly show a notification.
-  // Once all that has happened, there is no real reason to do it again. We
-  // only send one ping per day, so we aren't going to do that again. And
-  // the only time we ever show a second notification is 7 days after the
-  // first one, so we aren't going to do that again either.
-  // If the other process didn't take those actions, there is no reason that
-  // this process would take them.
-  // If the other process fails, this one will most likely fail for the same
-  // reason.
-  // So we'll just bail if we can't get the mutex quickly.
-  RegistryMutex regMutex;
-  if (!regMutex.Acquire()) {
-    return NS_ERROR_NOT_AVAILABLE;
-  }
-
-  // Check that Firefox ran recently, if not then stop here.
-  // Also stop if no timestamp was found, which most likely indicates
-  // that Firefox was not yet run.
-  bool ranRecently = false;
-  if (!aForce && (!CheckIfAppRanRecently(&ranRecently) || !ranRecently)) {
-    return NS_ERROR_FAILURE;
-  }
-
-  DefaultBrowserResult defaultBrowserResult = GetDefaultBrowserInfo();
-  DefaultBrowserInfo browserInfo{};
-  if (defaultBrowserResult.isOk()) {
-    browserInfo = defaultBrowserResult.unwrap();
-  } else {
-    browserInfo.currentDefaultBrowser = Browser::Error;
-    browserInfo.previousDefaultBrowser = Browser::Error;
-  }
-
-  DefaultPdfResult defaultPdfResult = GetDefaultPdfInfo();
-  DefaultPdfInfo pdfInfo{};
-  if (defaultPdfResult.isOk()) {
-    pdfInfo = defaultPdfResult.unwrap();
-  } else {
-    pdfInfo.currentDefaultPdf = PDFHandler::Error;
-  }
-
-  NotificationActivities activitiesPerformed;
-  // We block while waiting for the notification which prevents STA thread
-  // callbacks from running as the event loop won't run. Moving notification
-  // handling to an MTA thread prevents this conflict.
-  activitiesPerformed = MaybeShowNotification(
-      browserInfo, PromiseFlatString(aUniqueToken).get(), aForce);
-
-  HRESULT hr = SendDefaultAgentPing(browserInfo, pdfInfo, activitiesPerformed);
-  return SUCCEEDED(hr) ? NS_OK : NS_ERROR_FAILURE;
-}
-
-NS_IMETHODIMP
 DefaultAgent::AppRanRecently(bool* aRanRecently) {
   bool ranRecently = false;
   *aRanRecently = CheckIfAppRanRecently(&ranRecently) && ranRecently;
diff --git a/toolkit/mozapps/defaultagent/DefaultBrowser.cpp b/toolkit/mozapps/defaultagent/DefaultBrowser.cpp
index 87d3f62632..d9543665b7 100644
--- a/toolkit/mozapps/defaultagent/DefaultBrowser.cpp
+++ b/toolkit/mozapps/defaultagent/DefaultBrowser.cpp
@@ -184,17 +184,6 @@ BrowserResult TryGetReplacePreviousDefaultBrowser(Browser currentDefault) {
   return GetBrowserFromString(previousDefault);
 }
 
-DefaultBrowserResult GetDefaultBrowserInfo() {
-  DefaultBrowserInfo browserInfo;
-
-  MOZ_TRY_VAR(browserInfo.currentDefaultBrowser, TryGetDefaultBrowser());
-  MOZ_TRY_VAR(
-      browserInfo.previousDefaultBrowser,
-      TryGetReplacePreviousDefaultBrowser(browserInfo.currentDefaultBrowser));
-
-  return browserInfo;
-}
-
 // We used to prefix this key with the installation directory, but that causes
 // problems with our new "only one ping per day across installs" restriction.
 // To make sure all installations use consistent data, the value's name is
diff --git a/toolkit/mozapps/defaultagent/DefaultBrowser.h b/toolkit/mozapps/defaultagent/DefaultBrowser.h
index f1b940959f..081f3b9ccf 100644
--- a/toolkit/mozapps/defaultagent/DefaultBrowser.h
+++ b/toolkit/mozapps/defaultagent/DefaultBrowser.h
@@ -10,7 +10,6 @@
 #include <string>
 
 #include "mozilla/DefineEnum.h"
-#include "mozilla/WinHeaderOnlyUtils.h"
 
 namespace mozilla::default_agent {
 
@@ -24,9 +23,6 @@ struct DefaultBrowserInfo {
   Browser previousDefaultBrowser;
 };
 
-using DefaultBrowserResult = mozilla::WindowsErrorResult<DefaultBrowserInfo>;
-
-DefaultBrowserResult GetDefaultBrowserInfo();
 Browser GetDefaultBrowser();
 Browser GetReplacePreviousDefaultBrowser(Browser currentBrowser);
 
diff --git a/toolkit/mozapps/defaultagent/Notification.cpp b/toolkit/mozapps/defaultagent/Notification.cpp
index 961e57c9b3..39236eac15 100644
--- a/toolkit/mozapps/defaultagent/Notification.cpp
+++ b/toolkit/mozapps/defaultagent/Notification.cpp
@@ -7,616 +7,22 @@
 #include "Notification.h"
 
 #include <shlwapi.h>
-#include <wchar.h>
 #include <windows.h>
 #include <winnt.h>
 
-#include "mozilla/ArrayUtils.h"
-#include "mozilla/CmdLineAndEnvUtils.h"
-#include "mozilla/ErrorResult.h"
-#include "mozilla/mscom/EnsureMTA.h"
-#include "mozilla/intl/FileSource.h"
-#include "mozilla/intl/Localization.h"
-#include "mozilla/ShellHeaderOnlyUtils.h"
-#include "mozilla/UniquePtr.h"
-#include "mozilla/Unused.h"
-#include "mozilla/WinHeaderOnlyUtils.h"
-#include "nsString.h"
-#include "nsTArray.h"
-#include "nsWindowsHelpers.h"
-#include "readstrings.h"
-#include "updatererrors.h"
-#include "WindowsDefaultBrowser.h"
-
-#include "common.h"
-#include "DefaultBrowser.h"
-#include "EventLog.h"
-#include "Registry.h"
-#include "SetDefaultBrowser.h"
-
-#include "wintoastlib.h"
-
-using mozilla::intl::Localization;
+#include "nsLiteralString.h"
 
 #define SEVEN_DAYS_IN_SECONDS (7 * 24 * 60 * 60)
 
-// If the notification hasn't been activated or dismissed within 12 hours,
-// stop waiting for it.
-#define NOTIFICATION_WAIT_TIMEOUT_MS (12 * 60 * 60 * 1000)
+// If the notification hasn't been activated or dismissed within 11 hours 55
+// minutes, stop waiting for it.
+#define NOTIFICATION_WAIT_TIMEOUT_MS (11 * 60 * 60 * 1000 + 55 * 60 * 1000)
 // If the mutex hasn't been released within a few minutes, something is wrong
 // and we should give up on it
 #define MUTEX_TIMEOUT_MS (10 * 60 * 1000)
 
 namespace mozilla::default_agent {
 
-bool FirefoxInstallIsEnglish();
-
-static bool SetInitialNotificationShown(bool wasShown) {
-  return !RegistrySetValueBool(IsPrefixed::Unprefixed,
-                               L"InitialNotificationShown", wasShown)
-              .isErr();
-}
-
-static bool GetInitialNotificationShown() {
-  return RegistryGetValueBool(IsPrefixed::Unprefixed,
-                              L"InitialNotificationShown")
-      .unwrapOr(mozilla::Some(false))
-      .valueOr(false);
-}
-
-static bool ResetInitialNotificationShown() {
-  return RegistryDeleteValue(IsPrefixed::Unprefixed,
-                             L"InitialNotificationShown")
-      .isOk();
-}
-
-static bool SetFollowupNotificationShown(bool wasShown) {
-  return !RegistrySetValueBool(IsPrefixed::Unprefixed,
-                               L"FollowupNotificationShown", wasShown)
-              .isErr();
-}
-
-static bool GetFollowupNotificationShown() {
-  return RegistryGetValueBool(IsPrefixed::Unprefixed,
-                              L"FollowupNotificationShown")
-      .unwrapOr(mozilla::Some(false))
-      .valueOr(false);
-}
-
-static bool SetFollowupNotificationSuppressed(bool value) {
-  return !RegistrySetValueBool(IsPrefixed::Unprefixed,
-                               L"FollowupNotificationSuppressed", value)
-              .isErr();
-}
-
-static bool GetFollowupNotificationSuppressed() {
-  return RegistryGetValueBool(IsPrefixed::Unprefixed,
-                              L"FollowupNotificationSuppressed")
-      .unwrapOr(mozilla::Some(false))
-      .valueOr(false);
-}
-
-// Returns 0 if no value is set.
-static ULONGLONG GetFollowupNotificationRequestTime() {
-  return RegistryGetValueQword(IsPrefixed::Unprefixed, L"FollowupRequestTime")
-      .unwrapOr(mozilla::Some(0))
-      .valueOr(0);
-}
-
-// Returns false if no value is set.
-static bool GetPrefSetDefaultBrowserUserChoice() {
-  return RegistryGetValueBool(IsPrefixed::Prefixed,
-                              L"SetDefaultBrowserUserChoice")
-      .unwrapOr(mozilla::Some(false))
-      .valueOr(false);
-}
-
-struct ToastStrings {
-  mozilla::UniquePtr<wchar_t[]> text1;
-  mozilla::UniquePtr<wchar_t[]> text2;
-  mozilla::UniquePtr<wchar_t[]> action1;
-  mozilla::UniquePtr<wchar_t[]> action2;
-  mozilla::UniquePtr<wchar_t[]> relImagePath;
-};
-
-struct Strings {
-  // Toast notification button text is hard to localize because it tends to
-  // overflow. Thus, we have 3 different toast notifications:
-  //  - The initial notification, which includes a button with text like
-  //    "Ask me later". Since we cannot easily localize this, we will display
-  //    it only in English.
-  //  - The followup notification, to be shown if the user clicked "Ask me
-  //    later". Since we only have that button in English, we only need this
-  //    notification in English.
-  //  - The localized notification, which has much shorter button text to
-  //    (hopefully) prevent overflow: just "Yes" and "No". Since we no longer
-  //    have an "Ask me later" button, a followup localized notification is not
-  //    needed.
-  ToastStrings initialToast;
-  ToastStrings followupToast;
-  ToastStrings localizedToast;
-
-  // Returned pointer points within this struct and should not be freed.
-  const ToastStrings* GetToastStrings(NotificationType whichToast,
-                                      bool englishStrings) const {
-    if (!englishStrings) {
-      return &localizedToast;
-    }
-    if (whichToast == NotificationType::Initial) {
-      return &initialToast;
-    }
-    return &followupToast;
-  }
-};
-
-// Gets all strings out of the relevant INI files.
-// Returns true on success, false on failure
-static bool GetStrings(Strings& strings) {
-  mozilla::UniquePtr<wchar_t[]> installPath;
-  bool success = GetInstallDirectory(installPath);
-  if (!success) {
-    LOG_ERROR_MESSAGE(L"Failed to get install directory when getting strings");
-    return false;
-  }
-  nsTArray<nsCString> resIds = {"branding/brand.ftl"_ns,
-                                "browser/backgroundtasks/defaultagent.ftl"_ns};
-  RefPtr<Localization> l10n = Localization::Create(resIds, true);
-  nsAutoCString daHeaderText, daBodyText, daYesButton, daNoButton;
-  mozilla::ErrorResult daRv;
-  l10n->FormatValueSync("default-browser-notification-header-text"_ns, {},
-                        daHeaderText, daRv);
-  ENSURE_SUCCESS(daRv, false);
-  l10n->FormatValueSync("default-browser-notification-body-text"_ns, {},
-                        daBodyText, daRv);
-  ENSURE_SUCCESS(daRv, false);
-  l10n->FormatValueSync("default-browser-notification-yes-button-text"_ns, {},
-                        daYesButton, daRv);
-  ENSURE_SUCCESS(daRv, false);
-  l10n->FormatValueSync("default-browser-notification-no-button-text"_ns, {},
-                        daNoButton, daRv);
-  ENSURE_SUCCESS(daRv, false);
-
-  NS_ConvertUTF8toUTF16 daHeaderTextW(daHeaderText), daBodyTextW(daBodyText),
-      daYesButtonW(daYesButton), daNoButtonW(daNoButton);
-  strings.localizedToast.text1 =
-      mozilla::MakeUnique<wchar_t[]>(daHeaderTextW.Length() + 1);
-  wcsncpy(strings.localizedToast.text1.get(), daHeaderTextW.get(),
-          daHeaderTextW.Length() + 1);
-  strings.localizedToast.text2 =
-      mozilla::MakeUnique<wchar_t[]>(daBodyTextW.Length() + 1);
-  wcsncpy(strings.localizedToast.text2.get(), daBodyTextW.get(),
-          daBodyTextW.Length() + 1);
-  strings.localizedToast.action1 =
-      mozilla::MakeUnique<wchar_t[]>(daYesButtonW.Length() + 1);
-  wcsncpy(strings.localizedToast.action1.get(), daYesButtonW.get(),
-          daYesButtonW.Length() + 1);
-  strings.localizedToast.action2 =
-      mozilla::MakeUnique<wchar_t[]>(daNoButtonW.Length() + 1);
-  wcsncpy(strings.localizedToast.action2.get(), daNoButtonW.get(),
-          daNoButtonW.Length() + 1);
-  const wchar_t* iniFormat = L"%s\\defaultagent.ini";
-  int bufferSize = _scwprintf(iniFormat, installPath.get());
-  ++bufferSize;  // Extra character for terminating null
-  mozilla::UniquePtr<wchar_t[]> iniPath =
-      mozilla::MakeUnique<wchar_t[]>(bufferSize);
-  _snwprintf_s(iniPath.get(), bufferSize, _TRUNCATE, iniFormat,
-               installPath.get());
-
-  IniReader nonlocalizedReader(iniPath.get(), "Nonlocalized");
-  nonlocalizedReader.AddKey("InitialToastRelativeImagePath",
-                            &strings.initialToast.relImagePath);
-  nonlocalizedReader.AddKey("FollowupToastRelativeImagePath",
-                            &strings.followupToast.relImagePath);
-  nonlocalizedReader.AddKey("LocalizedToastRelativeImagePath",
-                            &strings.localizedToast.relImagePath);
-  int result = nonlocalizedReader.Read();
-  if (result != OK) {
-    LOG_ERROR_MESSAGE(L"Unable to read non-localized strings: %d", result);
-    return false;
-  }
-
-  return true;
-}
-
-static mozilla::WindowsError LaunchFirefoxToHandleDefaultBrowserAgent() {
-  // Could also be `MOZ_APP_NAME.exe`, but there's no generality to be gained:
-  // the WDBA is Firefox-only.
-  FilePathResult firefoxPathResult = GetRelativeBinaryPath(L"firefox.exe");
-  if (firefoxPathResult.isErr()) {
-    return firefoxPathResult.unwrapErr();
-  }
-  std::wstring firefoxPath = firefoxPathResult.unwrap();
-
-  _bstr_t cmd = firefoxPath.c_str();
-  // Omit argv[0] because ShellExecute doesn't need it.
-  _variant_t args(L"-to-handle-default-browser-agent");
-  _variant_t operation(L"open");
-  _variant_t directory;
-  _variant_t showCmd(SW_SHOWNORMAL);
-
-  // To prevent inheriting environment variables from the background task, we
-  // run Firefox via Explorer instead of our own process. This mimics the
-  // implementation of the Windows Launcher Process.
-  auto result =
-      ShellExecuteByExplorer(cmd, args, operation, directory, showCmd);
-  NS_ENSURE_TRUE(result.isOk(), result.unwrapErr());
-
-  return mozilla::WindowsError::CreateSuccess();
-}
-
-/*
- * Set the default browser.
- *
- * First check if we can directly write UserChoice, if so attempt that.
- * If we can't write UserChoice, or if the attempt fails, fall back to
- * showing the Default Apps page of Settings.
- *
- * @param aAumi The AUMI of the installation to set as default.
- */
-static void SetDefaultBrowserFromNotification(const wchar_t* aumi) {
-  nsresult rv = NS_ERROR_FAILURE;
-  if (GetPrefSetDefaultBrowserUserChoice()) {
-    rv = SetDefaultBrowserUserChoice(aumi);
-  }
-
-  if (NS_SUCCEEDED(rv)) {
-    mozilla::Unused << LaunchFirefoxToHandleDefaultBrowserAgent();
-  } else {
-    LOG_ERROR_MESSAGE(L"Failed to SetDefaultBrowserUserChoice: %#X",
-                      GetLastError());
-    LaunchModernSettingsDialogDefaultApps();
-  }
-}
-
-// This encapsulates the data that needs to be protected by a mutex because it
-// will be shared by the main thread and the handler thread.
-// To ensure the data is only written once, handlerDataHasBeenSet should be
-// initialized to false, then set to true when the handler writes data into the
-// structure.
-struct HandlerData {
-  NotificationActivities activitiesPerformed;
-  bool handlerDataHasBeenSet;
-};
-
-// The value that ToastHandler writes into should be a global. We can't control
-// when ToastHandler is called, and if this value isn't a global, ToastHandler
-// may be called and attempt to access this after it has been deconstructed.
-// Since this value is accessed by the handler thread and the main thread, it
-// is protected by a mutex (gHandlerMutex).
-// Since ShowNotification deconstructs the mutex, it might seem like once
-// ShowNotification exits, we can just rely on the inability to wait on an
-// invalid mutex to protect the deconstructed data, but it's possible that
-// we could deconstruct the mutex while the handler is holding it and is
-// already accessing the protected data.
-static HandlerData gHandlerReturnData;
-static HANDLE gHandlerMutex = INVALID_HANDLE_VALUE;
-
-class ToastHandler : public WinToastLib::IWinToastHandler {
- private:
-  NotificationType mWhichNotification;
-  HANDLE mEvent;
-  const std::wstring mAumiStr;
-
- public:
-  ToastHandler(NotificationType whichNotification, HANDLE event,
-               const wchar_t* aumi)
-      : mWhichNotification(whichNotification), mEvent(event), mAumiStr(aumi) {}
-
-  void FinishHandler(NotificationActivities& returnData) const {
-    SetReturnData(returnData);
-
-    BOOL success = SetEvent(mEvent);
-    if (!success) {
-      LOG_ERROR_MESSAGE(L"Event could not be set: %#X", GetLastError());
-    }
-  }
-
-  void SetReturnData(NotificationActivities& toSet) const {
-    DWORD result = WaitForSingleObject(gHandlerMutex, MUTEX_TIMEOUT_MS);
-    if (result == WAIT_TIMEOUT) {
-      LOG_ERROR_MESSAGE(L"Unable to obtain mutex ownership");
-      return;
-    } else if (result == WAIT_FAILED) {
-      LOG_ERROR_MESSAGE(L"Failed to wait on mutex: %#X", GetLastError());
-      return;
-    } else if (result == WAIT_ABANDONED) {
-      LOG_ERROR_MESSAGE(L"Found abandoned mutex");
-      ReleaseMutex(gHandlerMutex);
-      return;
-    }
-
-    // Only set this data once
-    if (!gHandlerReturnData.handlerDataHasBeenSet) {
-      gHandlerReturnData.activitiesPerformed = toSet;
-      gHandlerReturnData.handlerDataHasBeenSet = true;
-    }
-
-    BOOL success = ReleaseMutex(gHandlerMutex);
-    if (!success) {
-      LOG_ERROR_MESSAGE(L"Unable to release mutex ownership: %#X",
-                        GetLastError());
-    }
-  }
-
-  void toastActivated() const override {
-    NotificationActivities activitiesPerformed;
-    activitiesPerformed.type = mWhichNotification;
-    activitiesPerformed.shown = NotificationShown::Shown;
-    activitiesPerformed.action = NotificationAction::ToastClicked;
-
-    // Notification strings are written to indicate the default browser is
-    // restored to Firefox when the notification body is clicked to prevent
-    // ambiguity when buttons aren't pressed.
-    SetDefaultBrowserFromNotification(mAumiStr.c_str());
-
-    FinishHandler(activitiesPerformed);
-  }
-
-  void toastActivated(int actionIndex) const override {
-    NotificationActivities activitiesPerformed;
-    activitiesPerformed.type = mWhichNotification;
-    activitiesPerformed.shown = NotificationShown::Shown;
-    // Override this below
-    activitiesPerformed.action = NotificationAction::NoAction;
-
-    if (actionIndex == 0) {
-      // "Make Firefox the default" button, on both the initial and followup
-      // notifications. "Yes" button on the localized notification.
-      activitiesPerformed.action = NotificationAction::MakeFirefoxDefaultButton;
-
-      SetDefaultBrowserFromNotification(mAumiStr.c_str());
-    } else if (actionIndex == 1) {
-      // Do nothing. As long as we don't call
-      // SetFollowupNotificationRequestTime, there will be no followup
-      // notification.
-      activitiesPerformed.action = NotificationAction::DismissedByButton;
-    }
-
-    FinishHandler(activitiesPerformed);
-  }
-
-  void toastDismissed(WinToastDismissalReason state) const override {
-    NotificationActivities activitiesPerformed;
-    activitiesPerformed.type = mWhichNotification;
-    activitiesPerformed.shown = NotificationShown::Shown;
-    // Override this below
-    activitiesPerformed.action = NotificationAction::NoAction;
-
-    if (state == WinToastDismissalReason::TimedOut) {
-      activitiesPerformed.action = NotificationAction::DismissedByTimeout;
-    } else if (state == WinToastDismissalReason::ApplicationHidden) {
-      activitiesPerformed.action =
-          NotificationAction::DismissedByApplicationHidden;
-    } else if (state == WinToastDismissalReason::UserCanceled) {
-      activitiesPerformed.action = NotificationAction::DismissedToActionCenter;
-    }
-
-    FinishHandler(activitiesPerformed);
-  }
-
-  void toastFailed() const override {
-    NotificationActivities activitiesPerformed;
-    activitiesPerformed.type = mWhichNotification;
-    activitiesPerformed.shown = NotificationShown::Error;
-    activitiesPerformed.action = NotificationAction::NoAction;
-
-    LOG_ERROR_MESSAGE(L"Toast notification failed to display");
-    FinishHandler(activitiesPerformed);
-  }
-};
-
-// This function blocks until the shown notification is activated or dismissed.
-static NotificationActivities ShowNotification(
-    NotificationType whichNotification, const wchar_t* aumi) {
-  // Initially set the value that will be returned to error. If the notification
-  // is shown successfully, we'll update it.
-  NotificationActivities activitiesPerformed = {whichNotification,
-                                                NotificationShown::Error,
-                                                NotificationAction::NoAction};
-
-  bool isEnglishInstall = FirefoxInstallIsEnglish();
-
-  Strings strings;
-  if (!GetStrings(strings)) {
-    return activitiesPerformed;
-  }
-  const ToastStrings* toastStrings =
-      strings.GetToastStrings(whichNotification, isEnglishInstall);
-
-  mozilla::mscom::EnsureMTA([&] {
-    using namespace WinToastLib;
-
-    if (!WinToast::isCompatible()) {
-      LOG_ERROR_MESSAGE(L"System is not compatible with WinToast");
-      return;
-    }
-    WinToast::instance()->setAppName(L"" MOZ_APP_DISPLAYNAME);
-    std::wstring aumiStr = aumi;
-    WinToast::instance()->setAppUserModelId(aumiStr);
-    WinToast::instance()->setShortcutPolicy(
-        WinToastLib::WinToast::SHORTCUT_POLICY_REQUIRE_NO_CREATE);
-    WinToast::WinToastError error;
-    if (!WinToast::instance()->initialize(&error)) {
-      LOG_ERROR_MESSAGE(WinToast::strerror(error).c_str());
-      return;
-    }
-
-    // This event object will let the handler notify us when it has handled the
-    // notification.
-    nsAutoHandle event(CreateEventW(nullptr, TRUE, FALSE, nullptr));
-    if (event.get() == nullptr) {
-      LOG_ERROR_MESSAGE(L"Unable to create event object: %#X", GetLastError());
-      return;
-    }
-
-    bool success = false;
-    if (whichNotification == NotificationType::Initial) {
-      success = SetInitialNotificationShown(true);
-    } else {
-      success = SetFollowupNotificationShown(true);
-    }
-    if (!success) {
-      // Return early in this case to prevent the notification from being shown
-      // on every run.
-      LOG_ERROR_MESSAGE(L"Unable to set notification as displayed");
-      return;
-    }
-
-    // We need the absolute image path, not the relative path.
-    mozilla::UniquePtr<wchar_t[]> installPath;
-    success = GetInstallDirectory(installPath);
-    if (!success) {
-      LOG_ERROR_MESSAGE(L"Failed to get install directory for the image path");
-      return;
-    }
-    const wchar_t* absPathFormat = L"%s\\%s";
-    int bufferSize = _scwprintf(absPathFormat, installPath.get(),
-                                toastStrings->relImagePath.get());
-    ++bufferSize;  // Extra character for terminating null
-    mozilla::UniquePtr<wchar_t[]> absImagePath =
-        mozilla::MakeUnique<wchar_t[]>(bufferSize);
-    _snwprintf_s(absImagePath.get(), bufferSize, _TRUNCATE, absPathFormat,
-                 installPath.get(), toastStrings->relImagePath.get());
-
-    // This is used to protect gHandlerReturnData.
-    gHandlerMutex = CreateMutexW(nullptr, TRUE, nullptr);
-    if (gHandlerMutex == nullptr) {
-      LOG_ERROR_MESSAGE(L"Unable to create mutex: %#X", GetLastError());
-      return;
-    }
-    // Automatically close this mutex when this function exits.
-    nsAutoHandle autoMutex(gHandlerMutex);
-    // No need to initialize gHandlerReturnData.activitiesPerformed, since it
-    // will be set by the handler. But we do need to initialize
-    // gHandlerReturnData.handlerDataHasBeenSet so the handler knows that no
-    // data has been set yet.
-    gHandlerReturnData.handlerDataHasBeenSet = false;
-    success = ReleaseMutex(gHandlerMutex);
-    if (!success) {
-      LOG_ERROR_MESSAGE(L"Unable to release mutex ownership: %#X",
-                        GetLastError());
-    }
-
-    // Finally ready to assemble the notification and dispatch it.
-    WinToastTemplate toastTemplate =
-        WinToastTemplate(WinToastTemplate::ImageAndText02);
-    toastTemplate.setTextField(toastStrings->text1.get(),
-                               WinToastTemplate::FirstLine);
-    toastTemplate.setTextField(toastStrings->text2.get(),
-                               WinToastTemplate::SecondLine);
-    toastTemplate.addAction(toastStrings->action1.get());
-    toastTemplate.addAction(toastStrings->action2.get());
-    toastTemplate.setImagePath(absImagePath.get());
-    toastTemplate.setScenario(WinToastTemplate::Scenario::Reminder);
-    ToastHandler* handler =
-        new ToastHandler(whichNotification, event.get(), aumi);
-    INT64 id = WinToast::instance()->showToast(toastTemplate, handler, &error);
-    if (id < 0) {
-      LOG_ERROR_MESSAGE(WinToast::strerror(error).c_str());
-      return;
-    }
-
-    DWORD result =
-        WaitForSingleObject(event.get(), NOTIFICATION_WAIT_TIMEOUT_MS);
-    // Don't return after these errors. Attempt to hide the notification.
-    if (result == WAIT_FAILED) {
-      LOG_ERROR_MESSAGE(L"Unable to wait on event object: %#X", GetLastError());
-    } else if (result == WAIT_TIMEOUT) {
-      LOG_ERROR_MESSAGE(L"Timed out waiting for event object");
-    } else {
-      result = WaitForSingleObject(gHandlerMutex, MUTEX_TIMEOUT_MS);
-      if (result == WAIT_TIMEOUT) {
-        LOG_ERROR_MESSAGE(L"Unable to obtain mutex ownership");
-        // activitiesPerformed is already set to error. No change needed.
-      } else if (result == WAIT_FAILED) {
-        LOG_ERROR_MESSAGE(L"Failed to wait on mutex: %#X", GetLastError());
-        // activitiesPerformed is already set to error. No change needed.
-      } else if (result == WAIT_ABANDONED) {
-        LOG_ERROR_MESSAGE(L"Found abandoned mutex");
-        ReleaseMutex(gHandlerMutex);
-        // activitiesPerformed is already set to error. No change needed.
-      } else {
-        // Mutex is being held. It is safe to access gHandlerReturnData.
-        // If gHandlerReturnData.handlerDataHasBeenSet is false, the handler
-        // never ran. Use the error value activitiesPerformed already contains.
-        if (gHandlerReturnData.handlerDataHasBeenSet) {
-          activitiesPerformed = gHandlerReturnData.activitiesPerformed;
-        }
-
-        success = ReleaseMutex(gHandlerMutex);
-        if (!success) {
-          LOG_ERROR_MESSAGE(L"Unable to release mutex ownership: %#X",
-                            GetLastError());
-        }
-      }
-    }
-
-    if (!WinToast::instance()->hideToast(id)) {
-      LOG_ERROR_MESSAGE(L"Failed to hide notification");
-    }
-  });
-  return activitiesPerformed;
-}
-
-// Previously this function checked that the Firefox build was using English.
-// This was checked because of the peculiar way we were localizing toast
-// notifications where we used a completely different set of strings in English.
-//
-// We've since unified the notification flows but need to clean up unused code
-// and config files - Bug 1826375.
-bool FirefoxInstallIsEnglish() { return false; }
-
-// If a notification is shown, this function will block until the notification
-// is activated or dismissed.
-// aumi is the App User Model ID.
-NotificationActivities MaybeShowNotification(
-    const DefaultBrowserInfo& browserInfo, const wchar_t* aumi, bool force) {
-  // Default to not showing a notification. Any other value will be returned
-  // directly from ShowNotification.
-  NotificationActivities activitiesPerformed = {NotificationType::Initial,
-                                                NotificationShown::NotShown,
-                                                NotificationAction::NoAction};
-
-  // Reset notification state machine, user setting default browser to Firefox
-  // is a strong signal that they intend to have it as the default browser.
-  if (browserInfo.currentDefaultBrowser == Browser::Firefox) {
-    ResetInitialNotificationShown();
-  }
-
-  bool initialNotificationShown = GetInitialNotificationShown();
-  if (!initialNotificationShown || force) {
-    if ((browserInfo.currentDefaultBrowser == Browser::EdgeWithBlink &&
-         browserInfo.previousDefaultBrowser == Browser::Firefox) ||
-        force) {
-      return ShowNotification(NotificationType::Initial, aumi);
-    }
-    return activitiesPerformed;
-  }
-  activitiesPerformed.type = NotificationType::Followup;
-
-  ULONGLONG followupNotificationRequestTime =
-      GetFollowupNotificationRequestTime();
-  bool followupNotificationRequested = followupNotificationRequestTime != 0;
-  bool followupNotificationShown = GetFollowupNotificationShown();
-  if (followupNotificationRequested && !followupNotificationShown &&
-      !GetFollowupNotificationSuppressed()) {
-    ULONGLONG secondsSinceRequestTime =
-        SecondsPassedSince(followupNotificationRequestTime);
-
-    if (secondsSinceRequestTime >= SEVEN_DAYS_IN_SECONDS) {
-      // If we go to show the followup notification and the user has already
-      // changed the default browser, permanently suppress the followup since
-      // it's no longer relevant.
-      if (browserInfo.currentDefaultBrowser == Browser::EdgeWithBlink) {
-        return ShowNotification(NotificationType::Followup, aumi);
-      } else {
-        SetFollowupNotificationSuppressed(true);
-      }
-    }
-  }
-  return activitiesPerformed;
-}
-
 std::string GetStringForNotificationType(NotificationType type) {
   switch (type) {
     case NotificationType::Initial:
diff --git a/toolkit/mozapps/defaultagent/Notification.h b/toolkit/mozapps/defaultagent/Notification.h
index 210c55f559..e4e007088d 100644
--- a/toolkit/mozapps/defaultagent/Notification.h
+++ b/toolkit/mozapps/defaultagent/Notification.h
@@ -7,7 +7,9 @@
 #ifndef __DEFAULT_BROWSER_NOTIFICATION_H__
 #define __DEFAULT_BROWSER_NOTIFICATION_H__
 
-#include "DefaultBrowser.h"
+#include <string>
+
+#include "nsStringFwd.h"
 
 namespace mozilla::default_agent {
 
@@ -39,9 +41,6 @@ struct NotificationActivities {
   NotificationAction action;
 };
 
-NotificationActivities MaybeShowNotification(
-    const DefaultBrowserInfo& browserInfo, const wchar_t* aumi, bool force);
-
 // These take enum values and get strings suitable for telemetry
 std::string GetStringForNotificationType(NotificationType type);
 std::string GetStringForNotificationShown(NotificationShown shown);
diff --git a/toolkit/mozapps/defaultagent/ScheduledTask.cpp b/toolkit/mozapps/defaultagent/ScheduledTask.cpp
index a9cd647c03..c867e59b76 100644
--- a/toolkit/mozapps/defaultagent/ScheduledTask.cpp
+++ b/toolkit/mozapps/defaultagent/ScheduledTask.cpp
@@ -13,14 +13,11 @@
 #include <comutil.h>
 #include <taskschd.h>
 
-#include "readstrings.h"
-#include "updatererrors.h"
 #include "EventLog.h"
 #include "mozilla/RefPtr.h"
 #include "mozilla/ScopeExit.h"
 #include "mozilla/UniquePtr.h"
 #include "mozilla/WinHeaderOnlyUtils.h"
-#include "WindowsDefaultBrowser.h"
 
 #include "DefaultBrowser.h"
 
diff --git a/toolkit/mozapps/defaultagent/SetDefaultBrowser.cpp b/toolkit/mozapps/defaultagent/SetDefaultBrowser.cpp
index 8bc0889e67..6d829ff045 100644
--- a/toolkit/mozapps/defaultagent/SetDefaultBrowser.cpp
+++ b/toolkit/mozapps/defaultagent/SetDefaultBrowser.cpp
@@ -6,17 +6,16 @@
 #include <windows.h>
 #include <appmodel.h>
 #include <shlobj.h>  // for SHChangeNotify and IApplicationAssociationRegistration
-#include <functional>
 #include <timeapi.h>
 
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/CmdLineAndEnvUtils.h"
 #include "mozilla/RefPtr.h"
+#include "mozilla/Result.h"
 #include "mozilla/UniquePtr.h"
 #include "mozilla/WindowsVersion.h"
 #include "mozilla/WinHeaderOnlyUtils.h"
 #include "WindowsUserChoice.h"
-#include "nsThreadUtils.h"
 
 #include "EventLog.h"
 #include "SetDefaultBrowser.h"
@@ -70,6 +69,77 @@ static bool AddMillisecondsToSystemTime(SYSTEMTIME& aSystemTime,
   return true;
 }
 
+/*
+ * Takes two times: the start time and the current time, and returns the number
+ * of seconds left before the current time hits the next minute from the start
+ * time. Used to check if we are within the same minute as the start time and
+ * how much time we have left to perform an operation in the same minute.
+ *
+ * Used with user choice hashes, which have to be written to the registry
+ * in the same minute as they are generated.
+ *
+ * Example 1:
+ * operationStartTime - 10m 20s 800ms
+ * currentTime - 10m 22s 0ms
+ * The next minute is 11, so the return value is 11m - 10m 22s 0ms, converted to
+ * milliseconds.
+ *
+ * Example 2:
+ * operationStartTime - 10m 59s 800ms
+ * currentTime - 11m 0s 0ms
+ * The next minute is 11, but the minute the operation started on was 10, so the
+ * time to the next minute is 0 (because the current time is already at the next
+ * minute).
+ *
+ * @param operationStartTime
+ * @param currentTime
+ *
+ * @returns     the number of milliseconds left from the current time to the
+ * next minute from operationStartTime, or zero if the currentTime is already at
+ * the next minute or greater
+ */
+static WORD GetMillisecondsToNextMinute(SYSTEMTIME operationStartTime,
+                                        SYSTEMTIME currentTime) {
+  SYSTEMTIME operationStartTimeMinute = operationStartTime;
+  SYSTEMTIME currentTimeMinute = currentTime;
+
+  // Zero out the seconds and milliseconds so that we can confirm they are the
+  // same minutes
+  operationStartTimeMinute.wSecond = 0;
+  operationStartTimeMinute.wMilliseconds = 0;
+
+  currentTimeMinute.wSecond = 0;
+  currentTimeMinute.wMilliseconds = 0;
+
+  // Convert to a 64 bit value so we can compare them directly
+  FILETIME fileTime1;
+  FILETIME fileTime2;
+  if (!::SystemTimeToFileTime(&operationStartTimeMinute, &fileTime1) ||
+      !::SystemTimeToFileTime(&currentTimeMinute, &fileTime2)) {
+    // Error: report that there is 0 milliseconds till the next minute
+    return 0;
+  }
+
+  // The minutes for both times have to be the same, so confirm that they are,
+  // and if they aren't, return 0 milliseconds to indicate that we're already
+  // not on the minute that operationStartTime was on
+  if ((fileTime1.dwLowDateTime != fileTime2.dwLowDateTime) ||
+      (fileTime1.dwHighDateTime != fileTime2.dwHighDateTime)) {
+    return 0;
+  }
+
+  // The minutes are the same; determine the number of milliseconds left until
+  // the next minute
+  const WORD secondsToMilliseconds = 1000;
+  const WORD minutesToSeconds = 60;
+
+  // 1 minute converted to milliseconds - (the current second converted to
+  // milliseconds + the current milliseconds)
+  return (1 * minutesToSeconds * secondsToMilliseconds) -
+         ((currentTime.wSecond * secondsToMilliseconds) +
+          currentTime.wMilliseconds);
+}
+
 // Compare two SYSTEMTIMEs as FILETIME after clearing everything
 // below minutes.
 static bool CheckEqualMinutes(SYSTEMTIME aSystemTime1,
@@ -149,6 +219,75 @@ static bool SetUserChoiceRegistry(const wchar_t* aExt, const wchar_t* aProgID,
   return true;
 }
 
+struct LaunchExeErr {};
+using LaunchExeResult =
+    mozilla::Result<std::tuple<DWORD, mozilla::UniquePtr<wchar_t[]>>,
+                    LaunchExeErr>;
+
+static LaunchExeResult LaunchExecutable(const wchar_t* exePath, int aArgsLength,
+                                        const wchar_t* const* aArgs) {
+  const wchar_t* args[] = {exePath};
+  mozilla::UniquePtr<wchar_t[]> cmdLine(mozilla::MakeCommandLine(
+      mozilla::ArrayLength(args), const_cast<wchar_t**>(args), aArgsLength,
+      const_cast<wchar_t**>(aArgs)));
+
+  PROCESS_INFORMATION pi;
+  STARTUPINFOW si = {sizeof(si)};
+  si.dwFlags = STARTF_USESHOWWINDOW;
+  si.wShowWindow = SW_HIDE;
+
+  if (!::CreateProcessW(exePath, cmdLine.get(), nullptr, nullptr, FALSE, 0,
+                        nullptr, nullptr, &si, &pi)) {
+    HRESULT hr = HRESULT_FROM_WIN32(GetLastError());
+    LOG_ERROR(hr);
+    return Err(LaunchExeErr());
+  }
+
+  nsAutoHandle process(pi.hProcess);
+  nsAutoHandle mainThread(pi.hThread);
+
+  DWORD exitCode;
+  if (::WaitForSingleObject(process.get(), INFINITE) == WAIT_OBJECT_0 &&
+      ::GetExitCodeProcess(process.get(), &exitCode)) {
+    return std::make_tuple(exitCode, std::move(cmdLine));
+  }
+
+  return Err(LaunchExeErr());
+}
+
+static bool LaunchPowershell(const wchar_t* command,
+                             const wchar_t* powershellPath) {
+  const wchar_t* args[] = {
+      L"-NoProfile",  // ensure nothing is monkeying with powershell
+      L"-c",
+      command,
+  };
+
+  return LaunchExecutable(powershellPath, mozilla::ArrayLength(args), args)
+      .map([](auto result) {
+        auto& [exitCode, regCmdLine] = result;
+        bool success = (exitCode == 0);
+        if (!success) {
+          LOG_ERROR_MESSAGE(L"%s returned failure exitCode %d",
+                            regCmdLine.get(), exitCode);
+        }
+        return success;
+      })
+      .unwrapOr(false);
+}
+
+static bool FindPowershell(mozilla::UniquePtr<wchar_t[]>& powershellPath) {
+  auto exePath = mozilla::MakeUnique<wchar_t[]>(MAX_PATH + 1);
+  if (!ConstructSystem32Path(L"WindowsPowershell\\v1.0\\powershell.exe",
+                             exePath.get(), MAX_PATH + 1)) {
+    LOG_ERROR_MESSAGE(L"Failed to construct path to powershell.exe");
+    return false;
+  }
+
+  powershellPath.swap(exePath);
+  return true;
+}
+
 /*
  * Set an association with a UserChoice key
  *
@@ -165,7 +304,9 @@ static bool SetUserChoiceRegistry(const wchar_t* aExt, const wchar_t* aProgID,
 static bool SetUserChoice(const wchar_t* aExt, const wchar_t* aSid,
                           const wchar_t* aProgID, bool inMsix) {
   if (inMsix) {
-    LOG_ERROR_MESSAGE(L"SetUserChoice does not work on MSIX builds.");
+    LOG_ERROR_MESSAGE(
+        L"SetUserChoice should not be called on MSIX builds. Call "
+        L"SetDefaultExtensionHandlersUserChoiceImplMsix instead.");
     return false;
   }
 
@@ -298,6 +439,247 @@ nsresult SetDefaultExtensionHandlersUserChoice(
   return rv;
 }
 
+/*
+ * Takes the list of file extension pairs and fills a list of program ids for
+ * each pair.
+ *
+ * @param aFileExtensions array of file association pairs to
+ * set as default, like `[ ".pdf", "FirefoxPDF" ]`.
+ */
+static nsresult GenerateProgramIDs(const nsTArray<nsString>& aFileExtensions,
+                                   nsTArray<nsString>& progIDs) {
+  for (size_t i = 0; i + 1 < aFileExtensions.Length(); i += 2) {
+    const wchar_t* fileExtension = aFileExtensions[i].get();
+
+    // Formatting the ProgID here prevents using this helper to target arbitrary
+    // ProgIDs.
+    mozilla::UniquePtr<wchar_t[]> progID;
+    nsresult rv = GetMsixProgId(fileExtension, progID);
+    if (NS_FAILED(rv)) {
+      LOG_ERROR_MESSAGE(L"Failed to retrieve MSIX progID for %s",
+                        fileExtension);
+      return rv;
+    }
+
+    progIDs.AppendElement(nsString(progID.get()));
+  }
+
+  return NS_OK;
+}
+
+/*
+ * Takes the list of file extension pairs and a matching list of program ids for
+ * each of those pairs and verifies that the system is successfully to match
+ * each.
+ *
+ * @param aFileExtensions array of file association pairs to set as default,
+ * like `[ ".pdf", "FirefoxPDF" ]`.
+ * @param aProgIDs array of program ids. The order of this array matches the
+ * file extensions parameter.
+ */
+static nsresult VerifyUserDefaults(const nsTArray<nsString>& aFileExtensions,
+                                   const nsTArray<nsString>& aProgIDs) {
+  for (size_t i = 0; i + 1 < aFileExtensions.Length(); i += 2) {
+    const wchar_t* fileExtension = aFileExtensions[i].get();
+
+    if (!VerifyUserDefault(fileExtension, aProgIDs[i / 2].get())) {
+      return NS_ERROR_WDBA_REJECTED;
+    }
+  }
+
+  return NS_OK;
+}
+
+/*
+ * Queries the system for the minimum resolution (or tick time) in milliseconds
+ * that can be used with ::Sleep. If a Sleep is not triggered with a time
+ * divisible by the tick time, control can return to the thread before the time
+ * specified to Sleep.
+ *
+ * @param defaultValue  what to return if the system query fails.
+ */
+static UINT GetSystemSleepIntervalInMilliseconds(UINT defaultValue) {
+  TIMECAPS timeCapabilities;
+  bool timeCapsFetchSuccessful =
+      (MMSYSERR_NOERROR ==
+       timeGetDevCaps(&timeCapabilities, sizeof(timeCapabilities)));
+  if (!timeCapsFetchSuccessful) {
+    return defaultValue;
+  }
+
+  return timeCapabilities.wPeriodMin > 0 ? timeCapabilities.wPeriodMin
+                                         : defaultValue;
+}
+
+/*
+ * MSIX implementation for SetDefaultExtensionHandlersUserChoice.
+ *
+ * Due to the fact that MSIX builds run in a virtual, walled off environment,
+ * calling into the Win32 registry APIs doesn't work to set registry keys.
+ * MSIX builds access a virtual registry.
+ *
+ * Sends a "script" via command line to Powershell to modify the registry
+ * in an executable that is outside of the walled garden MSIX FX package
+ * environment, which is the only way to do that so far. Only works
+ * on slightly older versions of Windows 11 (older than 23H2).
+ *
+ * This was originally done using calls to Reg.exe, but permissions can't
+ * be changed that way, requiring using Powershell to call into .Net functions
+ * directly. Launching Powershell is slow (on the order of a second on some
+ * systems) so this method jams the calls to do everything into one launch of
+ * Powershell, to make it as quick as possible.
+ *
+ */
+static nsresult SetDefaultExtensionHandlersUserChoiceImplMsix(
+    const wchar_t* aAumi, const wchar_t* const aSid,
+    const nsTArray<nsString>& aFileExtensions) {
+  mozilla::UniquePtr<wchar_t[]> exePath;
+  if (!FindPowershell(exePath)) {
+    LOG_ERROR_MESSAGE(L"Could not locate Powershell");
+    return NS_ERROR_FAILURE;
+  }
+
+  // The following is the start of the script that will be sent to Powershell.
+  // In includes a function; calls to the function get appended per file
+  // extension, done below.
+  nsString startScript(
+      uR"(
+# Force exceptions to stop execution
+$ErrorActionPreference = 'Stop'
+
+function Set-DefaultHandlerRegistry($Path, $ProgID, $Hash) {
+  $Path = "$Path\UserChoice"
+  $CurrentUser = [Microsoft.Win32.Registry]::CurrentUser
+
+  # DeleteSubKey throws if we don't have sufficient permissions to delete key,
+  # signaling failure to launching process.
+  #
+  # Note: DeleteSubKeyTree fails when DENY permissions are set on key, whereas
+  # DeleteSubKey succeeds.
+  $CurrentUser.DeleteSubKey($Path, $false)
+  $key = $CurrentUser.CreateSubKey($Path)
+
+  $StringType = [Microsoft.Win32.RegistryValueKind]::String
+  $key.SetValue('ProgID', $ProgID, $StringType)
+  $key.SetValue('Hash', $Hash, $StringType)
+}
+
+)");  // Newlines in the above powershell script at the end are important!!!
+
+  // NOTE!!!! CreateProcess / calling things on the command line has a character
+  // count limit. For CMD.exe, it's 8K. For CreateProcessW, it's technically
+  // 32K. I can't find documentation about Powershell, but think 8K is safe to
+  // assume as a good maximum. The above script is about 1000 characters, and we
+  // will append another 100 characters at most per extension, so we'd need to
+  // be setting about 70 handlers at once to worry about the theoretical limit.
+  // Which we won't do. So the length shouldn't be a problem.
+  if (aFileExtensions.Length() >= 70) {
+    LOG_ERROR_MESSAGE(
+        L"SetDefaultExtensionHandlersUserChoiceImplMsix can't cope with 70 or "
+        L"more file extensions at once. Please break it up into multiple calls "
+        L"with fewer extensions per call.");
+    return NS_ERROR_FAILURE;
+  }
+
+  // NOTE!!!!
+  // User choice hashes have to be generated and written to the registry in the
+  // same minute. So we do everything we can upfront before we get to the hash
+  // generation, to ensure that hash generation and the call to Powershell to
+  // write to the registry has as much time as possible to run.
+
+  // Program ID fetch / generation might be slow, so do that ahead of time.
+  nsTArray<nsString> progIDs;
+  nsresult rv = GenerateProgramIDs(aFileExtensions, progIDs);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsString scriptBuffer;
+
+  // Everyting in the loop below should succeed or fail reasonably fast (within
+  // 20 milliseconds or something well under a second) besides the Powershell
+  // call. The Powershell call itself will either fail or succeed and break out
+  // of the loop, so repeating 10 times should be fine and is mostly to allow
+  // for getting the timing right with the user choice hash generation happening
+  // in the same minute - meaning this should likely only happen twice through
+  // the loop at most.
+  for (int i = 0; i < 10; i++) {
+    // Pre-allocate the memory for the scriptBuffer upfront so that we don't
+    // have to keep allocating every time Append is called.
+    const int scriptBufferCapacity = 16 * 1024;
+    scriptBuffer = startScript;
+    scriptBuffer.SetCapacity(scriptBufferCapacity);
+
+    SYSTEMTIME hashTimestamp;
+    ::GetSystemTime(&hashTimestamp);
+
+    // Time critical stuff starts here:
+
+    for (size_t i = 0; i + 1 < aFileExtensions.Length(); i += 2) {
+      const wchar_t* fileExtension = aFileExtensions[i].get();
+
+      nsAutoString keyPath;
+      AppendAssociationKeyPath(fileExtension, keyPath);
+
+      auto hashWchar = GenerateUserChoiceHash(
+          fileExtension, aSid, progIDs[i / 2].get(), hashTimestamp);
+      if (!hashWchar) {
+        return NS_ERROR_FAILURE;
+      }
+      auto hash = nsDependentString(hashWchar.get());
+
+      // Append a line to the script buffer in the form:
+      // Set-DefaultHandlerRegistry $RegistryKeyPath $ProgID $UserChoiceHash
+      scriptBuffer += u"Set-DefaultHandlerRegistry "_ns + keyPath + u" "_ns +
+                      progIDs[i / 2] + u" "_ns + hash + u"\n"_ns;
+    }
+
+    // The hash changes at the end of each minute, so check that the hash should
+    // be the same by the time we're done writing.
+    const ULONGLONG kWriteTimingThresholdMilliseconds = 2000;
+
+    // Generating the hash could have taken some time, so figure out what time
+    // we are at right now.
+    SYSTEMTIME writeEndTimestamp;
+    ::GetSystemTime(&writeEndTimestamp);
+
+    // Check if we have enough time to launch Powershell or if we should sleep
+    // to the next minute and try again
+    auto millisecondsLeftUntilNextMinute =
+        GetMillisecondsToNextMinute(hashTimestamp, writeEndTimestamp);
+    if (millisecondsLeftUntilNextMinute >= kWriteTimingThresholdMilliseconds) {
+      break;
+    }
+
+    LOG_ERROR_MESSAGE(
+        L"Hash is too close to next minute, sleeping until next minute to "
+        L"ensure that hash generation matches write to registry.");
+
+    UINT sleepUntilNextMinuteBufferMilliseconds =
+        GetSystemSleepIntervalInMilliseconds(
+            50);  // Default to 50ms if we can't figure out the right interval
+                  // to sleep for
+    ::Sleep(millisecondsLeftUntilNextMinute +
+            (sleepUntilNextMinuteBufferMilliseconds * 2));
+
+    // Try again, if we have any attempts left
+  }
+
+  // Call Powershell to set the registry keys now - this is the really time
+  // consuming thing 250ms to launch on a VM in a reasonably fast case, possibly
+  // a lot slower on other systems
+  bool powershellSuccessful =
+      LaunchPowershell(scriptBuffer.get(), exePath.get());
+  if (!powershellSuccessful) {
+    // If powershell failed, it likely means that something got mucked with
+    // the registry and that Windows is popping up notifications to the user,
+    // so don't try again right now, so as to not overwhelm the user and annoy
+    // them.
+    return NS_ERROR_FAILURE;
+  }
+
+  // Validate now
+  return VerifyUserDefaults(aFileExtensions, progIDs);
+}
+
 nsresult SetDefaultExtensionHandlersUserChoiceImpl(
     const wchar_t* aAumi, const wchar_t* const aSid,
     const nsTArray<nsString>& aFileExtensions) {
@@ -306,9 +688,8 @@ nsresult SetDefaultExtensionHandlersUserChoiceImpl(
       GetCurrentPackageFullName(&pfnLen, nullptr) != APPMODEL_ERROR_NO_PACKAGE;
 
   if (inMsix) {
-    // MSIX packages can not meaningfully modify the registry keys related to
-    // default handlers
-    return NS_ERROR_FAILURE;
+    return SetDefaultExtensionHandlersUserChoiceImplMsix(aAumi, aSid,
+                                                         aFileExtensions);
   }
 
   for (size_t i = 0; i + 1 < aFileExtensions.Length(); i += 2) {
diff --git a/toolkit/mozapps/defaultagent/defaultagent.ini b/toolkit/mozapps/defaultagent/defaultagent.ini
deleted file mode 100644
index 9300b20c46..0000000000
--- a/toolkit/mozapps/defaultagent/defaultagent.ini
+++ /dev/null
@@ -1,9 +0,0 @@
-; This Source Code Form is subject to the terms of the Mozilla Public
-; License, v. 2.0. If a copy of the MPL was not distributed with this
-; file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-; This file is in the UTF-8 encoding
-[Nonlocalized]
-InitialToastRelativeImagePath=browser/VisualElements/VisualElements_150.png
-FollowupToastRelativeImagePath=browser/VisualElements/VisualElements_150.png
-LocalizedToastRelativeImagePath=browser/VisualElements/VisualElements_150.png
diff --git a/toolkit/mozapps/defaultagent/moz.build b/toolkit/mozapps/defaultagent/moz.build
index 86b68c6371..f8ae506d9c 100644
--- a/toolkit/mozapps/defaultagent/moz.build
+++ b/toolkit/mozapps/defaultagent/moz.build
@@ -15,6 +15,7 @@ UNIFIED_SOURCES += [
     "DefaultBrowser.cpp",
     "DefaultPDF.cpp",
     "EventLog.cpp",
+    "Notification.cpp",
     "Policy.cpp",
     "Registry.cpp",
     "ScheduledTask.cpp",
@@ -25,21 +26,6 @@ UNIFIED_SOURCES += [
     "WindowsMutex.cpp",
 ]
 
-SOURCES += [
-    "/third_party/WinToast/wintoastlib.cpp",
-    "/toolkit/mozapps/update/common/readstrings.cpp",
-    "Notification.cpp",
-]
-
-# Suppress warnings from third-party code.
-SOURCES["/third_party/WinToast/wintoastlib.cpp"].flags += [
-    "-Wno-implicit-fallthrough",
-    "-Wno-nonportable-include-path",  # Needed for wintoastlib.h including "Windows.h"
-]
-SOURCES["Notification.cpp"].flags += [
-    "-Wno-nonportable-include-path",  # Needed for wintoastlib.h including "Windows.h"
-]
-
 EXPORTS.mozilla += [
     "DefaultAgent.h",
     "WindowsMutex.h",
@@ -52,9 +38,7 @@ USE_LIBS += [
 LOCAL_INCLUDES += [
     "/browser/components/shell/",
     "/other-licenses/nsis/Contrib/CityHash/cityhash",
-    "/third_party/WinToast",
     "/toolkit/components/jsoncpp/include",
-    "/toolkit/mozapps/update/common",
 ]
 
 OS_LIBS += [
@@ -98,8 +82,6 @@ for var in ("MOZ_APP_BASENAME", "MOZ_APP_DISPLAYNAME", "MOZ_APP_VENDOR"):
 DEFINES["UNICODE"] = True
 DEFINES["_UNICODE"] = True
 
-FINAL_TARGET_FILES += ["defaultagent.ini"]
-
 FINAL_LIBRARY = "xul"
 
 if CONFIG["ENABLE_TESTS"]:
diff --git a/toolkit/mozapps/defaultagent/nsIDefaultAgent.idl b/toolkit/mozapps/defaultagent/nsIDefaultAgent.idl
index 7e78e1b30d..8472dea3af 100644
--- a/toolkit/mozapps/defaultagent/nsIDefaultAgent.idl
+++ b/toolkit/mozapps/defaultagent/nsIDefaultAgent.idl
@@ -52,20 +52,6 @@ interface nsIDefaultAgent : nsISupports
   void uninstall(in AString aUniqueToken);
 
   /**
-  * Actually performs the default agent task, which currently means generating
-  * and sending our telemetry ping and possibly showing a notification to the
-  * user if their browser has switched from Firefox to Edge with Blink.
-  *
-  * @param {AString} aUniqueToken
-  *        A unique identifier for this installation; the same one provided when
-  *        the task was registered.
-  * @param {boolean} aForce
-  *        For debugging, forces the task to run even if it has run in the last
-  *        24 hours, and forces the notification to show.
-  */
-  void doTask(in AString aUniqueToken, in boolean aForce);
-
-  /**
   * Checks that the main app ran recently.
   *
   * @return {boolean} true if the app ran recently.
diff --git a/toolkit/mozapps/defaultagent/proxy/main.cpp b/toolkit/mozapps/defaultagent/proxy/main.cpp
index 53efdcb9ae..7ba63c2095 100644
--- a/toolkit/mozapps/defaultagent/proxy/main.cpp
+++ b/toolkit/mozapps/defaultagent/proxy/main.cpp
@@ -7,10 +7,8 @@
 #include <windows.h>
 #include <shlwapi.h>
 #include <objbase.h>
-#include <string.h>
 #include <filesystem>
 
-#include "../ScheduledTask.h"
 #include "../ScheduledTaskRemove.h"
 #include "mozilla/CmdLineAndEnvUtils.h"
 
diff --git a/toolkit/mozapps/defaultagent/proxy/moz.build b/toolkit/mozapps/defaultagent/proxy/moz.build
index 40d7655dfa..3ff6932ac2 100644
--- a/toolkit/mozapps/defaultagent/proxy/moz.build
+++ b/toolkit/mozapps/defaultagent/proxy/moz.build
@@ -17,7 +17,6 @@ UNIFIED_SOURCES += [
 SOURCES += [
     "/browser/components/shell/WindowsDefaultBrowser.cpp",
     "/other-licenses/nsis/Contrib/CityHash/cityhash/city.cpp",
-    "/toolkit/mozapps/update/common/readstrings.cpp",
 ]
 
 LOCAL_INCLUDES += [
diff --git a/toolkit/mozapps/downloads/DownloadLastDir.sys.mjs b/toolkit/mozapps/downloads/DownloadLastDir.sys.mjs
index da0439dcc5..dfd5d2cd26 100644
--- a/toolkit/mozapps/downloads/DownloadLastDir.sys.mjs
+++ b/toolkit/mozapps/downloads/DownloadLastDir.sys.mjs
@@ -48,7 +48,7 @@ var observer = {
     "nsISupportsWeakReference",
   ]),
 
-  observe(aSubject, aTopic, aData) {
+  observe(aSubject, aTopic) {
     switch (aTopic) {
       case "last-pb-context-exited":
         gDownloadLastDirFile = null;
diff --git a/toolkit/mozapps/downloads/DownloadUtils.sys.mjs b/toolkit/mozapps/downloads/DownloadUtils.sys.mjs
index 3bf97f3c9e..6684a73699 100644
--- a/toolkit/mozapps/downloads/DownloadUtils.sys.mjs
+++ b/toolkit/mozapps/downloads/DownloadUtils.sys.mjs
@@ -610,7 +610,7 @@ function convertTimeUnitsUnits(timeValue, aIndex) {
  *        Error message to log or an array of strings to concat
  */
 // function log(aMsg) {
-//   let msg = "DownloadUtils.jsm: " + (aMsg.join ? aMsg.join("") : aMsg);
+//   let msg = "DownloadUtils.sys.mjs: " + (aMsg.join ? aMsg.join("") : aMsg);
 //   Services.console.logStringMessage(msg);
 //   dump(msg + "\n");
 // }
diff --git a/toolkit/mozapps/downloads/HelperAppDlg.sys.mjs b/toolkit/mozapps/downloads/HelperAppDlg.sys.mjs
index 66f77d38e4..01d1a518d8 100644
--- a/toolkit/mozapps/downloads/HelperAppDlg.sys.mjs
+++ b/toolkit/mozapps/downloads/HelperAppDlg.sys.mjs
@@ -72,33 +72,19 @@ nsUnknownContentTypeDialogProgressListener.prototype = {
   },
 
   // Ignore onProgressChange, onProgressChange64, onStateChange, onLocationChange, onSecurityChange, onContentBlockingEvent and onRefreshAttempted notifications.
-  onProgressChange(
-    aWebProgress,
-    aRequest,
-    aCurSelfProgress,
-    aMaxSelfProgress,
-    aCurTotalProgress,
-    aMaxTotalProgress
-  ) {},
+  onProgressChange() {},
 
-  onProgressChange64(
-    aWebProgress,
-    aRequest,
-    aCurSelfProgress,
-    aMaxSelfProgress,
-    aCurTotalProgress,
-    aMaxTotalProgress
-  ) {},
+  onProgressChange64() {},
 
-  onStateChange(aWebProgress, aRequest, aStateFlags, aStatus) {},
+  onStateChange() {},
 
-  onLocationChange(aWebProgress, aRequest, aLocation, aFlags) {},
+  onLocationChange() {},
 
-  onSecurityChange(aWebProgress, aRequest, aState) {},
+  onSecurityChange() {},
 
-  onContentBlockingEvent(aWebProgress, aRequest, aEvent) {},
+  onContentBlockingEvent() {},
 
-  onRefreshAttempted(aWebProgress, aURI, aDelay, aSameURI) {
+  onRefreshAttempted() {
     return true;
   },
 };
@@ -309,7 +295,7 @@ nsUnknownContentTypeDialog.prototype = {
       var picker =
         Cc["@mozilla.org/filepicker;1"].createInstance(nsIFilePicker);
       var windowTitle = bundle.GetStringFromName("saveDialogTitle");
-      picker.init(parent, windowTitle, nsIFilePicker.modeSave);
+      picker.init(parent.browsingContext, windowTitle, nsIFilePicker.modeSave);
       if (aDefaultFileName) {
         picker.defaultString = this.getFinalLeafName(aDefaultFileName);
       }
@@ -1270,7 +1256,7 @@ nsUnknownContentTypeDialog.prototype = {
       var nsIFilePicker = Ci.nsIFilePicker;
       var fp = Cc["@mozilla.org/filepicker;1"].createInstance(nsIFilePicker);
       fp.init(
-        this.mDialog,
+        this.mDialog.browsingContext,
         this.dialogElement("strings").getString("chooseAppFilePickerTitle"),
         nsIFilePicker.modeOpen
       );
diff --git a/toolkit/mozapps/downloads/tests/browser/browser_save_wrongextension.js b/toolkit/mozapps/downloads/tests/browser/browser_save_wrongextension.js
index 83e668076a..ad83bb3689 100644
--- a/toolkit/mozapps/downloads/tests/browser/browser_save_wrongextension.js
+++ b/toolkit/mozapps/downloads/tests/browser/browser_save_wrongextension.js
@@ -8,7 +8,7 @@ let url =
   "data:text/html,<a id='link' href='http://localhost:8000/thefile.js'>Link</a>";
 
 let MockFilePicker = SpecialPowers.MockFilePicker;
-MockFilePicker.init(window);
+MockFilePicker.init(window.browsingContext);
 
 let httpServer = null;
 
diff --git a/toolkit/mozapps/downloads/tests/browser/browser_unknownContentType_delayedbutton.js b/toolkit/mozapps/downloads/tests/browser/browser_unknownContentType_delayedbutton.js
index 06a5a9d238..9bd494e245 100644
--- a/toolkit/mozapps/downloads/tests/browser/browser_unknownContentType_delayedbutton.js
+++ b/toolkit/mozapps/downloads/tests/browser/browser_unknownContentType_delayedbutton.js
@@ -13,14 +13,14 @@ let UCTObserver = {
   opened: Promise.withResolvers(),
   closed: Promise.withResolvers(),
 
-  observe(aSubject, aTopic, aData) {
+  observe(aSubject, aTopic) {
     let win = aSubject;
 
     switch (aTopic) {
       case "domwindowopened":
         win.addEventListener(
           "load",
-          function onLoad(event) {
+          function onLoad() {
             // Let the dialog initialize
             SimpleTest.executeSoon(function () {
               UCTObserver.opened.resolve(win);
@@ -40,7 +40,7 @@ let UCTObserver = {
 };
 
 function waitDelay(delay) {
-  return new Promise((resolve, reject) => {
+  return new Promise(resolve => {
     /* eslint-disable mozilla/no-arbitrary-setTimeout */
     window.setTimeout(resolve, delay);
   });
diff --git a/toolkit/mozapps/downloads/tests/browser/browser_unknownContentType_dialog_layout.js b/toolkit/mozapps/downloads/tests/browser/browser_unknownContentType_dialog_layout.js
index 6755c1aadb..e42951696d 100644
--- a/toolkit/mozapps/downloads/tests/browser/browser_unknownContentType_dialog_layout.js
+++ b/toolkit/mozapps/downloads/tests/browser/browser_unknownContentType_dialog_layout.js
@@ -38,14 +38,14 @@ add_task(async function test_unknownContentType_dialog_layout() {
       opened: Promise.withResolvers(),
       closed: Promise.withResolvers(),
 
-      observe(aSubject, aTopic, aData) {
+      observe(aSubject, aTopic) {
         let win = aSubject;
 
         switch (aTopic) {
           case "domwindowopened":
             win.addEventListener(
               "load",
-              function onLoad(event) {
+              function onLoad() {
                 // Let the dialog initialize
                 SimpleTest.executeSoon(function () {
                   UCTObserver.opened.resolve(win);
diff --git a/toolkit/mozapps/downloads/tests/unit/test_lowMinutes.js b/toolkit/mozapps/downloads/tests/unit/test_lowMinutes.js
index 786da28b75..9076fa7c76 100644
--- a/toolkit/mozapps/downloads/tests/unit/test_lowMinutes.js
+++ b/toolkit/mozapps/downloads/tests/unit/test_lowMinutes.js
@@ -20,7 +20,7 @@ const { DownloadUtils } = ChromeUtils.importESModule(
  * @usage _("Hello World") -> prints "Hello World"
  * @usage _(1, 2, 3) -> prints "1 2 3"
  */
-var _ = function (some, debug, text, to) {
+var _ = function () {
   print(Array.from(arguments).join(" "));
 };
 
diff --git a/toolkit/mozapps/extensions/AddonManager.sys.mjs b/toolkit/mozapps/extensions/AddonManager.sys.mjs
index e4e51885cf..c69cf4029e 100644
--- a/toolkit/mozapps/extensions/AddonManager.sys.mjs
+++ b/toolkit/mozapps/extensions/AddonManager.sys.mjs
@@ -1610,10 +1610,10 @@ var AddonManagerInternal = {
 
     // Temporary hack until bug 520124 lands.
     // We can get here during synchronous startup, at which point it's
-    // considered unsafe (and therefore disallowed by AddonManager.jsm) to
+    // considered unsafe (and therefore disallowed by AddonManager.sys.mjs) to
     // access providers that haven't been initialized yet. Since this is when
     // XPIProvider is starting up, XPIProvider can't access itself via APIs
-    // going through AddonManager.jsm. Thankfully, this is the only use
+    // going through AddonManager.sys.mjs. Thankfully, this is the only use
     // of this API, and we know it's safe to use this API with both
     // providers; so we have this hack to allow bypassing the normal
     // safetey guard.
diff --git a/toolkit/mozapps/extensions/content/aboutaddons.css b/toolkit/mozapps/extensions/content/aboutaddons.css
index 3f4e80797a..2f5157bea3 100644
--- a/toolkit/mozapps/extensions/content/aboutaddons.css
+++ b/toolkit/mozapps/extensions/content/aboutaddons.css
@@ -643,12 +643,18 @@ panel-item[action="report"]::part(button) {
   text-decoration: none;
 }
 
-.inline-options-stack {
-  /* If the options browser triggers an alert we need room to show it. */
-  min-height: 250px;
+.addon-inline-options {
   width: 100%;
   background-color: white;
   margin-block: 4px;
+  /*
+   * Makes sure the browser minimal height is going to be the same as when
+   * this browser element was wrapper in a stack and a min-height was necessary
+   * for the prompts to fit inside the browser element.
+   * That stack element has been removed as part of Bug 1881055, but keeping
+   * the min-height unchanged to avoid potential regressions in the short term.
+   */
+  min-height: 250px;
 }
 
 addon-permissions-list > .addon-detail-row {
diff --git a/toolkit/mozapps/extensions/content/aboutaddons.js b/toolkit/mozapps/extensions/content/aboutaddons.js
index 37687a8be7..39c4656210 100644
--- a/toolkit/mozapps/extensions/content/aboutaddons.js
+++ b/toolkit/mozapps/extensions/content/aboutaddons.js
@@ -1423,10 +1423,23 @@ class SidebarFooter extends HTMLElement {
       labelL10nId: "addons-settings-button",
       onClick: e => {
         e.preventDefault();
-        windowRoot.ownerGlobal.switchToTabHavingURI("about:preferences", true, {
-          ignoreFragment: "whenComparing",
-          triggeringPrincipal: systemPrincipal,
-        });
+        let hasAboutSettings = windowRoot.ownerGlobal.switchToTabHavingURI(
+          "about:settings",
+          false,
+          {
+            ignoreFragment: "whenComparing",
+          }
+        );
+        if (!hasAboutSettings) {
+          windowRoot.ownerGlobal.switchToTabHavingURI(
+            "about:preferences",
+            true,
+            {
+              ignoreFragment: "whenComparing",
+              triggeringPrincipal: systemPrincipal,
+            }
+          );
+        }
       },
     });
 
@@ -1695,6 +1708,7 @@ class InlineOptionsBrowser extends HTMLElement {
     browser.setAttribute("disableglobalhistory", "true");
     browser.setAttribute("messagemanagergroup", "webext-browsers");
     browser.setAttribute("id", "addon-inline-options");
+    browser.setAttribute("class", "addon-inline-options");
     browser.setAttribute("transparent", "true");
     browser.setAttribute("forcemessagemanager", "true");
     browser.setAttribute("autocompletepopup", "PopupAutoComplete");
@@ -1731,10 +1745,7 @@ class InlineOptionsBrowser extends HTMLElement {
       readyPromise = promiseEvent("load", browser, true);
     }
 
-    let stack = document.createXULElement("stack");
-    stack.classList.add("inline-options-stack");
-    stack.appendChild(browser);
-    this.appendChild(stack);
+    this.appendChild(browser);
     this.browser = browser;
 
     // Force bindings to apply synchronously.
diff --git a/toolkit/mozapps/extensions/content/aboutaddonsCommon.js b/toolkit/mozapps/extensions/content/aboutaddonsCommon.js
index 739e7629d7..9315e35861 100644
--- a/toolkit/mozapps/extensions/content/aboutaddonsCommon.js
+++ b/toolkit/mozapps/extensions/content/aboutaddonsCommon.js
@@ -237,7 +237,11 @@ async function installAddonsFromFilePicker() {
   ]);
   const nsIFilePicker = Ci.nsIFilePicker;
   var fp = Cc["@mozilla.org/filepicker;1"].createInstance(nsIFilePicker);
-  fp.init(window, dialogTitle.value, nsIFilePicker.modeOpenMultiple);
+  fp.init(
+    window.browsingContext,
+    dialogTitle.value,
+    nsIFilePicker.modeOpenMultiple
+  );
   try {
     fp.appendFilter(filterName.value, "*.xpi;*.jar;*.zip");
     fp.appendFilters(nsIFilePicker.filterAll);
diff --git a/toolkit/mozapps/extensions/internal/AddonRepository.sys.mjs b/toolkit/mozapps/extensions/internal/AddonRepository.sys.mjs
index e854e04b3c..e53e4af7a4 100644
--- a/toolkit/mozapps/extensions/internal/AddonRepository.sys.mjs
+++ b/toolkit/mozapps/extensions/internal/AddonRepository.sys.mjs
@@ -78,7 +78,7 @@ import { Log } from "resource://gre/modules/Log.sys.mjs";
 const LOGGER_ID = "addons.repository";
 
 // Create a new logger for use by the Addons Repository
-// (Requires AddonManager.jsm)
+// (Requires AddonManager.sys.mjs)
 var logger = Log.repository.getLogger(LOGGER_ID);
 
 function convertHTMLToPlainText(html) {
diff --git a/toolkit/mozapps/extensions/internal/AddonTestUtils.sys.mjs b/toolkit/mozapps/extensions/internal/AddonTestUtils.sys.mjs
index 7b30daa0e2..f53d32092d 100644
--- a/toolkit/mozapps/extensions/internal/AddonTestUtils.sys.mjs
+++ b/toolkit/mozapps/extensions/internal/AddonTestUtils.sys.mjs
@@ -298,7 +298,7 @@ export var AddonTestUtils = {
     // And scan for changes at startup
     Services.prefs.setIntPref("extensions.startupScanScopes", 15);
 
-    // By default, don't cache add-ons in AddonRepository.jsm
+    // By default, don't cache add-ons in AddonRepository.sys.mjs
     Services.prefs.setBoolPref("extensions.getAddons.cache.enabled", false);
 
     // Point update checks to the local machine for fast failures
@@ -567,7 +567,7 @@ export var AddonTestUtils = {
   },
 
   overrideCertDB() {
-    let verifyCert = async (file, result, cert, callback) => {
+    let verifyCert = async (file, result, signatureInfos, callback) => {
       if (
         result == Cr.NS_ERROR_SIGNED_JAR_NOT_SIGNED &&
         !this.useRealCertChecks &&
@@ -606,7 +606,16 @@ export var AddonTestUtils = {
             };
           }
 
-          return [callback, Cr.NS_OK, fakeCert];
+          return [
+            callback,
+            Cr.NS_OK,
+            [
+              {
+                signerCert: fakeCert,
+                signatureAlgorithm: Ci.nsIAppSignatureInfo.COSE_WITH_SHA256,
+              },
+            ],
+          ];
         } catch (e) {
           // If there is any error then just pass along the original results
         } finally {
@@ -621,7 +630,7 @@ export var AddonTestUtils = {
         }
       }
 
-      return [callback, result, cert];
+      return [callback, result, signatureInfos];
     };
 
     let FakeCertDB = {
@@ -644,10 +653,14 @@ export var AddonTestUtils = {
         this._genuine.openSignedAppFileAsync(
           root,
           file,
-          (result, zipReader, cert) => {
-            verifyCert(file.clone(), result, cert, callback).then(
-              ([callback, result, cert]) => {
-                callback.openSignedAppFileFinished(result, zipReader, cert);
+          (result, zipReader, signatureInfos) => {
+            verifyCert(file.clone(), result, signatureInfos, callback).then(
+              ([callback, result, signatureInfos]) => {
+                callback.openSignedAppFileFinished(
+                  result,
+                  zipReader,
+                  signatureInfos
+                );
               }
             );
           }
@@ -1730,7 +1743,7 @@ export var AddonTestUtils = {
    * @param {object} extension
    *        The return value of ExtensionTestUtils.loadExtension.
    *        For browser tests, see mochitest/tests/SimpleTest/ExtensionTestUtils.js
-   *        For xpcshell tests, see toolkit/components/extensions/ExtensionXPCShellUtils.jsm
+   *        For xpcshell tests, see toolkit/components/extensions/ExtensionXPCShellUtils.sys.mjs
    * @param {object} [options]
    *        Optional options.
    * @param {boolean} [options.expectPending = false]
diff --git a/toolkit/mozapps/extensions/internal/AddonUpdateChecker.sys.mjs b/toolkit/mozapps/extensions/internal/AddonUpdateChecker.sys.mjs
index a3935a26f9..5b7b10a764 100644
--- a/toolkit/mozapps/extensions/internal/AddonUpdateChecker.sys.mjs
+++ b/toolkit/mozapps/extensions/internal/AddonUpdateChecker.sys.mjs
@@ -26,7 +26,7 @@ import { Log } from "resource://gre/modules/Log.sys.mjs";
 const LOGGER_ID = "addons.update-checker";
 
 // Create a new logger for use by the Addons Update Checker
-// (Requires AddonManager.jsm)
+// (Requires AddonManager.sys.mjs)
 var logger = Log.repository.getLogger(LOGGER_ID);
 
 /**
diff --git a/toolkit/mozapps/extensions/internal/SitePermsAddonProvider.sys.mjs b/toolkit/mozapps/extensions/internal/SitePermsAddonProvider.sys.mjs
index ccac484a1e..7ca952dc8a 100644
--- a/toolkit/mozapps/extensions/internal/SitePermsAddonProvider.sys.mjs
+++ b/toolkit/mozapps/extensions/internal/SitePermsAddonProvider.sys.mjs
@@ -148,20 +148,30 @@ class SitePermsAddonWrapper {
     });
   }
 
-  get creator() {}
+  get creator() {
+    return undefined;
+  }
 
-  get homepageURL() {}
+  get homepageURL() {
+    return undefined;
+  }
 
-  get description() {}
+  get description() {
+    return undefined;
+  }
 
-  get fullDescription() {}
+  get fullDescription() {
+    return undefined;
+  }
 
   get version() {
     // We consider the previous implementation attempt (signed addons) to be the initial version,
     // hence the 2.0 for this approach.
     return "2.0";
   }
-  get updateDate() {}
+  get updateDate() {
+    return undefined;
+  }
 
   get isActive() {
     return true;
@@ -273,8 +283,6 @@ class SitePermsAddonWrapper {
 }
 
 class SitePermsAddonInstalling extends SitePermsAddonWrapper {
-  #install = null;
-
   /**
    * @param {string} siteOriginNoSuffix: The origin this addon is installed
    *                                     for, WITHOUT the suffix generated from
@@ -293,7 +301,6 @@ class SitePermsAddonInstalling extends SitePermsAddonWrapper {
     };
 
     super(siteOriginNoSuffix, [permission]);
-    this.#install = install;
   }
 
   get existingAddon() {
diff --git a/toolkit/mozapps/extensions/internal/XPIDatabase.sys.mjs b/toolkit/mozapps/extensions/internal/XPIDatabase.sys.mjs
index 5d1d2c1970..af0b02444a 100644
--- a/toolkit/mozapps/extensions/internal/XPIDatabase.sys.mjs
+++ b/toolkit/mozapps/extensions/internal/XPIDatabase.sys.mjs
@@ -117,7 +117,7 @@ const nsIFile = Components.Constructor(
 );
 
 // Create a new logger for use by the Addons XPI Provider Utils
-// (Requires AddonManager.jsm)
+// (Requires AddonManager.sys.mjs)
 var logger = Log.repository.getLogger(LOGGER_ID);
 
 const FILE_JSON_DB = "extensions.json";
diff --git a/toolkit/mozapps/extensions/internal/XPIInstall.sys.mjs b/toolkit/mozapps/extensions/internal/XPIInstall.sys.mjs
index 1a80407ad2..0402c2f2ca 100644
--- a/toolkit/mozapps/extensions/internal/XPIInstall.sys.mjs
+++ b/toolkit/mozapps/extensions/internal/XPIInstall.sys.mjs
@@ -99,6 +99,17 @@ const PREF_SELECTED_THEME = "extensions.activeThemeID";
 
 const TOOLKIT_ID = "toolkit@mozilla.org";
 
+ChromeUtils.defineLazyGetter(lazy, "MOZ_UNSIGNED_SCOPES", () => {
+  let result = 0;
+  if (AppConstants.MOZ_UNSIGNED_APP_SCOPE) {
+    result |= AddonManager.SCOPE_APPLICATION;
+  }
+  if (AppConstants.MOZ_UNSIGNED_SYSTEM_SCOPE) {
+    result |= AddonManager.SCOPE_SYSTEM;
+  }
+  return result;
+});
+
 /**
  * Returns a nsIFile instance for the given path, relative to the given
  * base file, if provided.
@@ -168,7 +179,7 @@ import { Log } from "resource://gre/modules/Log.sys.mjs";
 const LOGGER_ID = "addons.xpi";
 
 // Create a new logger for use by all objects in this Addons XPI Provider module
-// (Requires AddonManager.jsm)
+// (Requires AddonManager.sys.mjs)
 var logger = Log.repository.getLogger(LOGGER_ID);
 
 // Stores the ID of the theme which was selected during the last session,
@@ -316,13 +327,22 @@ XPIPackage = class XPIPackage extends Package {
   verifySignedStateForRoot(addonId, root) {
     return new Promise(resolve => {
       let callback = {
-        openSignedAppFileFinished(aRv, aZipReader, aCert) {
+        openSignedAppFileFinished(aRv, aZipReader, aSignatureInfos) {
+          // aSignatureInfos is an array of nsIAppSignatureInfo.
+          // In the future, this code can iterate through the array to
+          // determine if one of the verified signatures used a satisfactory
+          // algorithm and signing certificate.
+          // For now, any verified signature is acceptable.
+          let cert;
+          if (aRv == Cr.NS_OK && aSignatureInfos.length) {
+            cert = aSignatureInfos[0].signerCert;
+          }
           if (aZipReader) {
             aZipReader.close();
           }
           resolve({
-            signedState: getSignedStatus(aRv, aCert, addonId),
-            cert: aCert,
+            signedState: getSignedStatus(aRv, cert, addonId),
+            cert,
           });
         },
       };
@@ -872,10 +892,7 @@ function shouldVerifySignedState(aAddonType, aLocation) {
     return true;
   }
 
-  if (
-    aLocation.isBuiltin ||
-    aLocation.scope & AppConstants.MOZ_UNSIGNED_SCOPES
-  ) {
+  if (aLocation.isBuiltin || aLocation.scope & lazy.MOZ_UNSIGNED_SCOPES) {
     return false;
   }
 
diff --git a/toolkit/mozapps/extensions/internal/XPIProvider.sys.mjs b/toolkit/mozapps/extensions/internal/XPIProvider.sys.mjs
index d5ffd06d11..12d4fa1172 100644
--- a/toolkit/mozapps/extensions/internal/XPIProvider.sys.mjs
+++ b/toolkit/mozapps/extensions/internal/XPIProvider.sys.mjs
@@ -185,7 +185,7 @@ import { Log } from "resource://gre/modules/Log.sys.mjs";
 const LOGGER_ID = "addons.xpi";
 
 // Create a new logger for use by all objects in this Addons XPI Provider module
-// (Requires AddonManager.jsm)
+// (Requires AddonManager.sys.mjs)
 var logger = Log.repository.getLogger(LOGGER_ID);
 
 /**
diff --git a/toolkit/mozapps/extensions/test/browser/browser.toml b/toolkit/mozapps/extensions/test/browser/browser.toml
index 1daf6211f8..0b4a2d8f0a 100644
--- a/toolkit/mozapps/extensions/test/browser/browser.toml
+++ b/toolkit/mozapps/extensions/test/browser/browser.toml
@@ -156,6 +156,8 @@ https_first_disabled = true
 
 ["browser_sidebar_hidden_categories.js"]
 
+["browser_sidebar_preferences_button.js"]
+
 ["browser_sidebar_restore_category.js"]
 
 ["browser_subframe_install.js"]
diff --git a/toolkit/mozapps/extensions/test/browser/browser_html_options_ui.js b/toolkit/mozapps/extensions/test/browser/browser_html_options_ui.js
index c5bfa1022f..efe28cf218 100644
--- a/toolkit/mozapps/extensions/test/browser/browser_html_options_ui.js
+++ b/toolkit/mozapps/extensions/test/browser/browser_html_options_ui.js
@@ -115,13 +115,7 @@ add_task(async function testInlineOptions() {
     "The browser has the expected options URL"
   );
   is(url, card.addon.optionsURL, "Browser has the expected options URL loaded");
-  let stack = browser.closest("stack");
-  is(
-    browser.clientWidth,
-    stack.clientWidth,
-    "Browser should be the same width as its direct parent"
-  );
-  Assert.greater(stack.clientWidth, 0, "The stack has a width");
+  Assert.greater(browser.clientWidth, 0, "The browser has a width");
   ok(
     card.querySelector('[action="preferences"]').hidden,
     "The preferences option is hidden now"
@@ -163,8 +157,7 @@ add_task(async function testInlineOptions() {
   info("Switch back, check browser is shown");
   prefsBtn.click();
 
-  is(browser.clientWidth, stack.clientWidth, "The browser width is set again");
-  Assert.greater(stack.clientWidth, 0, "The stack has a width");
+  Assert.greater(browser.clientWidth, 0, "The browser has a width");
 
   await closeView(win);
   await extension.unload();
diff --git a/toolkit/mozapps/extensions/test/browser/browser_page_options_install_addon.js b/toolkit/mozapps/extensions/test/browser/browser_page_options_install_addon.js
index 5007731927..7bc7c08345 100644
--- a/toolkit/mozapps/extensions/test/browser/browser_page_options_install_addon.js
+++ b/toolkit/mozapps/extensions/test/browser/browser_page_options_install_addon.js
@@ -5,7 +5,7 @@
 // Tests bug 567127 - Add install button to the add-ons manager
 
 var MockFilePicker = SpecialPowers.MockFilePicker;
-MockFilePicker.init(window);
+MockFilePicker.init(window.browsingContext);
 
 async function checkInstallConfirmation(...names) {
   let notificationCount = 0;
diff --git a/toolkit/mozapps/extensions/test/browser/browser_sidebar_preferences_button.js b/toolkit/mozapps/extensions/test/browser/browser_sidebar_preferences_button.js
new file mode 100644
index 0000000000..91a631bca2
--- /dev/null
+++ b/toolkit/mozapps/extensions/test/browser/browser_sidebar_preferences_button.js
@@ -0,0 +1,73 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(async function testNoOtherTabsPresent() {
+  let addonsWin = await loadInitialView("extension");
+  let preferencesButton =
+    addonsWin.document.querySelector("#preferencesButton");
+
+  let preferencesPromise = BrowserTestUtils.waitForNewTab(
+    gBrowser,
+    "about:preferences"
+  );
+
+  preferencesButton.click();
+
+  let preferencesTab = await preferencesPromise;
+
+  is(
+    gBrowser.currentURI.spec,
+    "about:preferences",
+    "about:preferences should open if neither it nor about:settings are present"
+  );
+
+  gBrowser.removeTab(preferencesTab);
+
+  await closeView(addonsWin);
+});
+
+async function ensurePreferencesButtonFocusesTab(expectedUri) {
+  let addonsWin = await loadInitialView("extension");
+  let preferencesButton =
+    addonsWin.document.querySelector("#preferencesButton");
+
+  let tabCountBeforeClick = gBrowser.tabCount;
+  preferencesButton.click();
+  let tabCountAfterClick = gBrowser.tabCount;
+
+  is(
+    tabCountAfterClick,
+    tabCountBeforeClick,
+    "preferences button should not open new tabs"
+  );
+  is(
+    gBrowser.currentURI.spec,
+    expectedUri,
+    "the correct tab should be focused"
+  );
+
+  addonsWin.focus();
+  await closeView(addonsWin);
+}
+
+add_task(async function testAboutPreferencesPresent() {
+  await BrowserTestUtils.withNewTab("about:preferences", async () => {
+    await ensurePreferencesButtonFocusesTab("about:preferences");
+  });
+});
+
+add_task(async function testAboutSettingsPresent() {
+  await BrowserTestUtils.withNewTab("about:settings", async () => {
+    await ensurePreferencesButtonFocusesTab("about:settings");
+  });
+});
+
+add_task(async function testAboutSettingsAndPreferencesPresent() {
+  await BrowserTestUtils.withNewTab("about:settings", async () => {
+    await BrowserTestUtils.withNewTab("about:preferences", async () => {
+      await ensurePreferencesButtonFocusesTab("about:settings");
+    });
+  });
+});
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_corrupt.js b/toolkit/mozapps/extensions/test/xpcshell/test_corrupt.js
index 727c643763..33e81c13bd 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_corrupt.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_corrupt.js
@@ -196,7 +196,7 @@ add_task(async function test_after_corruption() {
 
   await Assert.rejects(
     promiseShutdownManager(),
-    /NotAllowedError: Could not open the file at .+ for writing/
+    /NotAllowedError: Could not write to `.+'/
   );
 });
 
@@ -211,6 +211,6 @@ add_task(async function test_after_second_restart() {
 
   await Assert.rejects(
     promiseShutdownManager(),
-    /NotAllowedError: Could not open the file at .+ for writing/
+    /NotAllowedError: Could not write to `.+'/
   );
 });
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_system_update_enterprisepolicy.js b/toolkit/mozapps/extensions/test/xpcshell/test_system_update_enterprisepolicy.js
index d36b97a3cc..e25890515f 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_system_update_enterprisepolicy.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_system_update_enterprisepolicy.js
@@ -44,12 +44,32 @@ const TEST_CONDITIONS = {
 add_task(async function test_update_disabled_by_policy() {
   await setupSystemAddonConditions(TEST_CONDITIONS, distroDir);
 
+  const TEST_POLICY_DATA = {
+    DisableSystemAddonUpdate: true,
+  };
   await EnterprisePolicyTesting.setupPolicyEngineWithJson({
-    policies: {
-      DisableSystemAddonUpdate: true,
-    },
+    policies: TEST_POLICY_DATA,
   });
 
+  Assert.deepEqual(
+    Services.policies.getActivePolicies(),
+    TEST_POLICY_DATA,
+    "Got the expected test policy data as the active policy " +
+      "(if this assertions fails, check your system for enterprise policies installed at system level)"
+  );
+
+  Assert.equal(
+    Services.policies.isAllowed("SysAddonUpdate"),
+    false,
+    "Expected SysAddonUpdate feature to be disabled by policies"
+  );
+
+  Assert.equal(
+    Services.prefs.getBoolPref("extensions.systemAddon.update.enabled"),
+    true,
+    "Expected system addon updates to not be already disabled through prefs"
+  );
+
   await updateAllSystemAddons(
     buildSystemAddonUpdates([
       {
diff --git a/toolkit/mozapps/handling/content/appChooser.js b/toolkit/mozapps/handling/content/appChooser.js
index 2958ad68b4..6c04717783 100644
--- a/toolkit/mozapps/handling/content/appChooser.js
+++ b/toolkit/mozapps/handling/content/appChooser.js
@@ -225,7 +225,7 @@ let dialog = {
     let title = await this.getChooseAppWindowTitle();
 
     var fp = Cc["@mozilla.org/filepicker;1"].createInstance(Ci.nsIFilePicker);
-    fp.init(window, title, Ci.nsIFilePicker.modeOpen);
+    fp.init(window.browsingContext, title, Ci.nsIFilePicker.modeOpen);
     fp.appendFilters(Ci.nsIFilePicker.filterApps);
 
     fp.open(rv => {
diff --git a/toolkit/mozapps/installer/packager.py b/toolkit/mozapps/installer/packager.py
index 29364045dd..f9d28d9c0c 100644
--- a/toolkit/mozapps/installer/packager.py
+++ b/toolkit/mozapps/installer/packager.py
@@ -63,7 +63,7 @@ class RemovedFiles(GeneratedFile):
             return
         if self.copier.contains(f):
             errors.error("Removal of packaged file(s): %s" % f)
-        self.content = f + "\n"
+        self.content += f.encode("utf-8") + b"\n"
 
 
 def split_define(define):
diff --git a/toolkit/mozapps/update/AppUpdater.sys.mjs b/toolkit/mozapps/update/AppUpdater.sys.mjs
index 6133fb613b..f837982b84 100644
--- a/toolkit/mozapps/update/AppUpdater.sys.mjs
+++ b/toolkit/mozapps/update/AppUpdater.sys.mjs
@@ -411,20 +411,6 @@ export class AppUpdater {
     return Services.sysinfo.getProperty("isPackagedApp");
   }
 
-  // true when updating in background is enabled.
-  get #updateStagingEnabled() {
-    LOG(
-      "AppUpdater:#updateStagingEnabled" +
-        "canStageUpdates: " +
-        this.aus.canStageUpdates
-    );
-    return (
-      !this.aus.disabled &&
-      !this.#updateDisabledByPackage &&
-      this.aus.canStageUpdates
-    );
-  }
-
   /**
    * Downloads an update mar or connects to an in-progress download.
    * Doesn't resolve until the update is ready to install, or a failure state
diff --git a/toolkit/mozapps/update/BackgroundUpdate.sys.mjs b/toolkit/mozapps/update/BackgroundUpdate.sys.mjs
index 28d0fc8538..3022c9ffde 100644
--- a/toolkit/mozapps/update/BackgroundUpdate.sys.mjs
+++ b/toolkit/mozapps/update/BackgroundUpdate.sys.mjs
@@ -570,7 +570,7 @@ export var BackgroundUpdate = {
     };
 
     try {
-      // Interacting with `TaskScheduler.jsm` can throw, so we'll catch.
+      // Interacting with `TaskScheduler.sys.mjs` can throw, so we'll catch.
       if (!enabled) {
         lazy.log.info(
           `${SLUG}: not scheduling background update: '${JSON.stringify(
diff --git a/toolkit/mozapps/update/UpdateService.sys.mjs b/toolkit/mozapps/update/UpdateService.sys.mjs
index 16ebf64ef3..34bf1b9e19 100644
--- a/toolkit/mozapps/update/UpdateService.sys.mjs
+++ b/toolkit/mozapps/update/UpdateService.sys.mjs
@@ -193,7 +193,7 @@ const WRITE_ERROR_DIR_ACCESS_DENIED = 68;
 const WRITE_ERROR_DELETE_BACKUP = 69;
 const WRITE_ERROR_EXTRACT = 70;
 
-// Error codes 80 through 99 are reserved for UpdateService.jsm and are not
+// Error codes 80 through 99 are reserved for UpdateService.sys.mjs and are not
 // defined in common/updatererrors.h
 const ERR_UPDATER_CRASHED = 89;
 const ERR_OLDER_VERSION_OR_SAME_BUILD = 90;
@@ -440,7 +440,7 @@ let gOtherInstancePollPromise;
  *
  * @return true if at least one other instance is running, false if not
  */
-function isOtherInstanceRunning(callback) {
+function isOtherInstanceRunning() {
   const checkEnabled = Services.prefs.getBoolPref(
     PREF_APP_UPDATE_CHECK_ONLY_INSTANCE_ENABLED,
     true
@@ -497,7 +497,7 @@ function waitForOtherInstances() {
   let iterations = 0;
   const maxIterations = Math.ceil(timeout / interval);
 
-  gOtherInstancePollPromise = new Promise(function (resolve, reject) {
+  gOtherInstancePollPromise = new Promise(function (resolve) {
     let poll = function () {
       iterations++;
       if (!isOtherInstanceRunning()) {
@@ -1907,7 +1907,7 @@ function pingStateAndStatusCodes(aUpdate, aStartup, aStatus) {
         stateCode = 13;
         break;
       // Note: Do not use stateCode 14 here. It is defined in
-      // UpdateTelemetry.jsm
+      // UpdateTelemetry.sys.mjs
       default:
         stateCode = 1;
     }
@@ -3352,10 +3352,10 @@ UpdateService.prototype = {
 
   /**
    * Notified when a timer fires
-   * @param   timer
+   * @param   _timer
    *          The timer that fired
    */
-  notify: function AUS_notify(timer) {
+  notify: function AUS_notify(_timer) {
     this._checkForBackgroundUpdates(true);
   },
 
@@ -3399,7 +3399,7 @@ UpdateService.prototype = {
       // See Bug 1599590.
       // Note that we exit unconditionally here if we are only doing manual
       // update checks, because manual update checking uses a completely
-      // different code path (AppUpdater.jsm creates its own nsIUpdateChecker),
+      // different code path (AppUpdater.sys.mjs creates its own nsIUpdateChecker),
       // bypassing this function completely.
       AUSTLMY.pingCheckCode(this._pingSuffix, AUSTLMY.CHK_DISABLED_BY_POLICY);
       return false;
@@ -4907,7 +4907,7 @@ UpdateManager.prototype = {
   /**
    * See nsIUpdateService.idl
    */
-  doInstallCleanup: async function UM_doInstallCleanup(isUninstall) {
+  doInstallCleanup: async function UM_doInstallCleanup() {
     LOG("UpdateManager:doInstallCleanup - cleaning up");
     let completionPromises = [];
 
@@ -4949,7 +4949,7 @@ UpdateManager.prototype = {
   /**
    * See nsIUpdateService.idl
    */
-  doUninstallCleanup: async function UM_doUninstallCleanup(isUninstall) {
+  doUninstallCleanup: async function UM_doUninstallCleanup() {
     LOG("UpdateManager:doUninstallCleanup - cleaning up.");
     let completionPromises = [];
 
@@ -5272,13 +5272,13 @@ export class CheckerService {
         return;
       }
 
-      let onLoad = event => {
+      let onLoad = _event => {
         request.removeEventListener("load", onLoad);
         LOG("CheckerService:#updateCheck - request got 'load' event");
         resolve(UPDATE_CHECK_LOAD_SUCCESS);
       };
       request.addEventListener("load", onLoad);
-      let onError = event => {
+      let onError = _event => {
         request.removeEventListener("error", onLoad);
         LOG("CheckerService:#updateCheck - request got 'error' event");
         resolve(UPDATE_CHECK_LOAD_ERROR);
@@ -5702,11 +5702,9 @@ Downloader.prototype = {
    * set of update patches.
    * @param   update
    *          A nsIUpdate object to select a patch from
-   * @param   updateDir
-   *          A nsIFile representing the update directory
    * @return  A nsIUpdatePatch object to download
    */
-  _selectPatch: function Downloader__selectPatch(update, updateDir) {
+  _selectPatch: function Downloader__selectPatch(update) {
     // Given an update to download, we will always try to download the patch
     // for a partial update over the patch for a full update.
 
@@ -5934,7 +5932,7 @@ Downloader.prototype = {
 
     // This function may return null, which indicates that there are no patches
     // to download.
-    this._patch = this._selectPatch(update, updateDir);
+    this._patch = this._selectPatch(update);
     if (!this._patch) {
       LOG("Downloader:downloadUpdate - no patch to download");
       AUSTLMY.pingDownloadCode(undefined, AUSTLMY.DWNLD_ERR_NO_UPDATE_PATCH);
diff --git a/toolkit/mozapps/update/UpdateTelemetry.sys.mjs b/toolkit/mozapps/update/UpdateTelemetry.sys.mjs
index 20fb0ab4a4..f3c350267c 100644
--- a/toolkit/mozapps/update/UpdateTelemetry.sys.mjs
+++ b/toolkit/mozapps/update/UpdateTelemetry.sys.mjs
@@ -316,7 +316,7 @@ export var AUSTLMY = {
    *        This value is also used to determine the key for the keyed scalar
    *        update.bitshresult (key is either "COMPLETE" or "PARTIAL")
    * @param aError
-   *        The BitsError that occurred. See Bits.jsm for details on BitsError.
+   *        The BitsError that occurred. See Bits.sys.mjs for details on BitsError.
    */
   pingBitsError: function UT_pingBitsError(aIsComplete, aError) {
     if (AppConstants.platform != "win") {
diff --git a/toolkit/mozapps/update/common/updatererrors.h b/toolkit/mozapps/update/common/updatererrors.h
index f2663d5b57..d3abf14ffe 100644
--- a/toolkit/mozapps/update/common/updatererrors.h
+++ b/toolkit/mozapps/update/common/updatererrors.h
@@ -10,7 +10,7 @@
 #define OK 0
 
 // Error codes that are no longer used should not be used again unless they
-// aren't used in client code (e.g. UpdateService.jsm, updates.js, etc.).
+// aren't used in client code (e.g. UpdateService.sys.mjs, updates.js, etc.).
 
 #define MAR_ERROR_EMPTY_ACTION_LIST 1
 #define LOADSOURCE_ERROR_WRONG_SIZE 2
@@ -26,8 +26,8 @@
 
 // Error codes 10-14 are related to memory allocation failures.
 // Note: If more memory allocation error codes are added, the implementation of
-// isMemoryAllocationErrorCode in UpdateService.jsm should be updated to account
-// for them.
+// isMemoryAllocationErrorCode in UpdateService.sys.mjs should be updated to
+// account for them.
 #define READ_STRINGS_MEM_ERROR 10
 #define ARCHIVE_READER_MEM_ERROR 11
 #define BSPATCH_MEM_ERROR 12
@@ -49,8 +49,8 @@
 
 // Error codes 24-33 and 49-58 are for the Windows maintenance service.
 // Note: If more maintenance service error codes are added, the implementations
-// of IsServiceSpecificErrorCode in updater.cpp and UpdateService.jsm should be
-// updated to account for them.
+// of IsServiceSpecificErrorCode in updater.cpp and UpdateService.sys.mjs should
+// be updated to account for them.
 #define SERVICE_UPDATER_COULD_NOT_BE_STARTED 24
 #define SERVICE_NOT_ENOUGH_COMMAND_LINE_ARGS 25
 #define SERVICE_UPDATER_SIGN_ERROR 26
@@ -79,8 +79,8 @@
 
 // Error codes 24-33 and 49-58 are for the Windows maintenance service.
 // Note: If more maintenance service error codes are added, the implementations
-// of IsServiceSpecificErrorCode in updater.cpp and UpdateService.jsm should be
-// updated to account for them.
+// of IsServiceSpecificErrorCode in updater.cpp and UpdateService.sys.mjs should
+// be updated to account for them.
 #define SERVICE_COULD_NOT_COPY_UPDATER 49
 #define SERVICE_STILL_APPLYING_TERMINATED 50
 #define SERVICE_STILL_APPLYING_NO_EXIT_CODE 51
@@ -112,7 +112,7 @@
 #define INVALID_CALLBACK_DIR_ERROR 78
 #define UPDATE_STATUS_UNCHANGED 79
 
-// Error codes 80 through 99 are reserved for UpdateService.jsm
+// Error codes 80 through 99 are reserved for UpdateService.sys.mjs
 
 // The following error codes are only used by updater.exe
 // when a fallback key exists for tests.
@@ -125,6 +125,6 @@
 #define SILENT_UPDATE_NEEDED_ELEVATION_ERROR 105
 #define WRITE_ERROR_BACKGROUND_TASK_SHARING_VIOLATION 106
 
-// Error codes 110 and 111 are reserved for UpdateService.jsm
+// Error codes 110 and 111 are reserved for UpdateService.sys.mjs
 
 #endif  // UPDATEERRORS_H
diff --git a/toolkit/mozapps/update/docs/BackgroundUpdates.rst b/toolkit/mozapps/update/docs/BackgroundUpdates.rst
index 7f97f58c74..d8a154cb39 100644
--- a/toolkit/mozapps/update/docs/BackgroundUpdates.rst
+++ b/toolkit/mozapps/update/docs/BackgroundUpdates.rst
@@ -65,7 +65,7 @@ observe and control these settings.
 
 But there are some other pieces of state which absolutely must come from a
 profile, such as the telemetry client ID and logging level settings (see
-`BackgroundTasksUtils.jsm <https://searchfox.org/mozilla-central/source/toolkit/components/backgroundtasks/BackgroundTasksUtils.jsm>`__).
+`BackgroundTasksUtils.sys.mjs <https://searchfox.org/mozilla-central/source/toolkit/components/backgroundtasks/BackgroundTasksUtils.sys.mjs>`__).
 
 This means that, in addition to our per-installation prefs, we also need
 to be able to identify and load a profile. To do that, we leverage `the profile
@@ -137,7 +137,7 @@ API <https://docs.microsoft.com/en-us/windows/win32/taskschd/task-scheduler-star
 on macOS this will use
 `launchd <https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/CreatingLaunchdJobs.html>`__.
 For platform-specific scheduling details, see the
-`TaskScheduler.jsm <https://searchfox.org/mozilla-central/source/toolkit/components/taskscheduler/TaskScheduler.jsm>`__
+`TaskScheduler.sys.mjs <https://searchfox.org/mozilla-central/source/toolkit/components/taskscheduler/TaskScheduler.sys.mjs>`__
 module.
 
 These background tasks are scheduled per OS user and run with that user’s
@@ -177,7 +177,7 @@ visible to users: see `bug 1775132
 
 After setting up this profile and reading all the configuration we need
 into it, the regular
-`UpdateService.jsm <https://searchfox.org/mozilla-central/source/toolkit/mozapps/update/UpdateService.jsm>`__
+`UpdateService.sys.mjs <https://searchfox.org/mozilla-central/source/toolkit/mozapps/update/UpdateService.sys.mjs>`__
 check process is initiated. To the greatest extent possible, this process is
 identical to what happens during any regular browsing session.
 
diff --git a/toolkit/mozapps/update/tests/browser/browser_elevationDialog.js b/toolkit/mozapps/update/tests/browser/browser_elevationDialog.js
index 6aa32a7fc9..639af1ffff 100644
--- a/toolkit/mozapps/update/tests/browser/browser_elevationDialog.js
+++ b/toolkit/mozapps/update/tests/browser/browser_elevationDialog.js
@@ -13,7 +13,7 @@ add_task(async function elevation_dialog() {
   let { startup } = Services;
   let appStartup = {
     QueryInterface: ChromeUtils.generateQI(["nsIAppStartup"]),
-    quit(mode) {
+    quit(_mode) {
       if (elevationDialog) {
         elevationDialog.close();
         elevationDialog = null;
@@ -120,7 +120,7 @@ function waitForElevationDialog() {
         var domwindow = aXULWindow.docShell.domWindow;
         domwindow.addEventListener("load", elevationDialogOnLoad, true);
       },
-      onCloseWindow: aXULWindow => {},
+      onCloseWindow: _aXULWindow => {},
     };
 
     Services.wm.addListener(listener);
diff --git a/toolkit/mozapps/update/tests/browser/head.js b/toolkit/mozapps/update/tests/browser/head.js
index a18a72e581..c5acdad8e4 100644
--- a/toolkit/mozapps/update/tests/browser/head.js
+++ b/toolkit/mozapps/update/tests/browser/head.js
@@ -487,7 +487,7 @@ function waitForAboutDialog() {
         var domwindow = aXULWindow.docShell.domWindow;
         domwindow.addEventListener("load", aboutDialogOnLoad, true);
       },
-      onCloseWindow: aXULWindow => {},
+      onCloseWindow: _aXULWindow => {},
     };
 
     Services.wm.addListener(listener);
diff --git a/toolkit/mozapps/update/tests/data/app_update.sjs b/toolkit/mozapps/update/tests/data/app_update.sjs
index 2081118547..1d5d23bfb5 100644
--- a/toolkit/mozapps/update/tests/data/app_update.sjs
+++ b/toolkit/mozapps/update/tests/data/app_update.sjs
@@ -79,7 +79,7 @@ function handleRequest(aRequest, aResponse) {
     let retries = 0;
     gSlowDownloadTimer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
     gSlowDownloadTimer.initWithCallback(
-      function (aTimer) {
+      function (_aTimer) {
         let continueFile = getTestDataFile(CONTINUE_DOWNLOAD);
         retries++;
         if (continueFile.exists() || retries == MAX_SLOW_RESPONSE_RETRIES) {
@@ -197,7 +197,7 @@ function respond(aResponse, aParams, aResponseString) {
     aResponse.processAsync();
     gSlowCheckTimer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
     gSlowCheckTimer.initWithCallback(
-      function (aTimer) {
+      function (_aTimer) {
         retries++;
         let continueFile = getTestDataFile(CONTINUE_CHECK);
         if (continueFile.exists() || retries == MAX_SLOW_RESPONSE_RETRIES) {
diff --git a/toolkit/mozapps/update/tests/data/shared.js b/toolkit/mozapps/update/tests/data/shared.js
index fc3d358586..60de6feeb8 100644
--- a/toolkit/mozapps/update/tests/data/shared.js
+++ b/toolkit/mozapps/update/tests/data/shared.js
@@ -922,7 +922,7 @@ async function continueFileHandler(leafName) {
     "Waiting for file to be deleted, path: " + continueFile.path,
     interval,
     retries
-  ).catch(e => {
+  ).catch(_e => {
     logTestInfo(
       "Continue file was not removed after checking " +
         retries +
diff --git a/toolkit/mozapps/update/tests/data/xpcshellUtilsAUS.js b/toolkit/mozapps/update/tests/data/xpcshellUtilsAUS.js
index e88a4418cb..4b12edf6f0 100644
--- a/toolkit/mozapps/update/tests/data/xpcshellUtilsAUS.js
+++ b/toolkit/mozapps/update/tests/data/xpcshellUtilsAUS.js
@@ -3766,7 +3766,7 @@ function checkFilesAfterUpdateSuccess(
           "xattr value changed"
         );
       },
-      reason => {
+      _reason => {
         Assert.fail(MAC_APP_XATTR_KEY + " xattr is missing!");
       }
     );
@@ -4233,9 +4233,9 @@ async function waitForUpdateDownload(aUpdates, aExpectedStatus) {
   }
   return new Promise(resolve =>
     gAUS.addDownloadListener({
-      onStartRequest: aRequest => {},
-      onProgress: (aRequest, aContext, aProgress, aMaxProgress) => {},
-      onStatus: (aRequest, aStatus, aStatusText) => {},
+      onStartRequest: _aRequest => {},
+      onProgress: (_aRequest, _aContext, _aProgress, _aMaxProgress) => {},
+      onStatus: (_aRequest, _aStatus, _aStatusText) => {},
       onStopRequest(request, status) {
         gAUS.removeDownloadListener(this);
         Assert.equal(
@@ -4552,7 +4552,7 @@ function adjustGeneralPaths() {
  * The timer callback to kill the process if it takes too long.
  */
 const gAppTimerCallback = {
-  notify: function TC_notify(aTimer) {
+  notify: function TC_notify(_aTimer) {
     gAppTimer = null;
     if (gProcess.isRunning) {
       logTestInfo("attempting to kill process");
@@ -4662,7 +4662,7 @@ function IncrementalDownload() {
 
 IncrementalDownload.prototype = {
   /* nsIIncrementalDownload */
-  init(uri, file, chunkSize, intervalInSeconds) {
+  init(uri, file, _chunkSize, _intervalInSeconds) {
     this._destination = file;
     this._URI = uri;
     this._finalURI = uri;
@@ -4729,7 +4729,7 @@ IncrementalDownload.prototype = {
   },
 
   /* nsIRequest */
-  cancel(aStatus) {
+  cancel(_aStatus) {
     throw Components.Exception("", Cr.NS_ERROR_NOT_IMPLEMENTED);
   },
   suspend() {
diff --git a/toolkit/mozapps/update/tests/marionette/test_no_window_update_restart.py b/toolkit/mozapps/update/tests/marionette/test_no_window_update_restart.py
index a8495064ef..9452a4fcd7 100644
--- a/toolkit/mozapps/update/tests/marionette/test_no_window_update_restart.py
+++ b/toolkit/mozapps/update/tests/marionette/test_no_window_update_restart.py
@@ -162,7 +162,9 @@ class TestNoWindowUpdateRestart(MarionetteTestCase):
             let UM = Cc["@mozilla.org/updates/update-manager;1"].getService(Ci.nsIUpdateManager);
             UM.QueryInterface(Ci.nsIObserver).observe(null, "um-reload-update-data", "skip-files");
 
-            let { UpdateListener } = ChromeUtils.import("resource://gre/modules/UpdateListener.jsm");
+            let { UpdateListener } = ChromeUtils.importESModule(
+                "resource://gre/modules/UpdateListener.sys.mjs"
+            );
             UpdateListener.reset();
 
             let { AppMenuNotifications } = ChromeUtils.importESModule(
diff --git a/toolkit/mozapps/update/tests/unit_aus_update/languagePackUpdates.js b/toolkit/mozapps/update/tests/unit_aus_update/languagePackUpdates.js
index 0ae35ef77a..9e23fab5e0 100644
--- a/toolkit/mozapps/update/tests/unit_aus_update/languagePackUpdates.js
+++ b/toolkit/mozapps/update/tests/unit_aus_update/languagePackUpdates.js
@@ -243,9 +243,9 @@ add_task(async function testRedownload() {
 
   let downloadCount = 0;
   let listener = {
-    onStartRequest: aRequest => {},
-    onProgress: (aRequest, aContext, aProgress, aMaxProgress) => {},
-    onStatus: (aRequest, aStatus, aStatusText) => {},
+    onStartRequest: _aRequest => {},
+    onProgress: (_aRequest, _aContext, _aProgress, _aMaxProgress) => {},
+    onStatus: (_aRequest, _aStatus, _aStatusText) => {},
     onStopRequest: (request, status) => {
       Assert.equal(
         status,
diff --git a/toolkit/mozapps/update/tests/unit_aus_update/multiUpdate.js b/toolkit/mozapps/update/tests/unit_aus_update/multiUpdate.js
index 3767a44feb..411b303331 100644
--- a/toolkit/mozapps/update/tests/unit_aus_update/multiUpdate.js
+++ b/toolkit/mozapps/update/tests/unit_aus_update/multiUpdate.js
@@ -73,14 +73,14 @@ async function downloadUpdate(appUpdateAuto, onDownloadStartCallback) {
   }
   let waitToStartPromise = new Promise(resolve => {
     let listener = {
-      onStartRequest: aRequest => {
+      onStartRequest: _aRequest => {
         gAUS.removeDownloadListener(listener);
         onDownloadStartCallback();
         resolve();
       },
-      onProgress: (aRequest, aContext, aProgress, aMaxProgress) => {},
-      onStatus: (aRequest, aStatus, aStatusText) => {},
-      onStopRequest(request, status) {},
+      onProgress: (_aRequest, _aContext, _aProgress, _aMaxProgress) => {},
+      onStatus: (_aRequest, _aStatus, _aStatusText) => {},
+      onStopRequest(_request, _status) {},
       QueryInterface: ChromeUtils.generateQI([
         "nsIRequestObserver",
         "nsIProgressEventSink",
@@ -149,7 +149,7 @@ async function testUpdateDoesNotDownload() {
   );
 
   let updateAvailableObserved = false;
-  let observer = (subject, topic, status) => {
+  let observer = (_subject, _topic, _status) => {
     updateAvailableObserved = true;
   };
   Services.obs.addObserver(observer, "update-available");
diff --git a/toolkit/mozapps/update/tests/unit_aus_update/updateSyncManager.js b/toolkit/mozapps/update/tests/unit_aus_update/updateSyncManager.js
index 9123f9e1e3..c705d536a4 100644
--- a/toolkit/mozapps/update/tests/unit_aus_update/updateSyncManager.js
+++ b/toolkit/mozapps/update/tests/unit_aus_update/updateSyncManager.js
@@ -79,7 +79,7 @@ add_task(async function () {
     await TestUtils.waitForCondition(
       () => syncManager.isOtherInstanceRunning(),
       "waiting for child process to take the lock"
-    ).catch(e => {
+    ).catch(_e => {
       // Rather than throwing out of waitForCondition(), catch and log the failure
       // manually so that we get output that's a bit more readable.
       Assert.ok(
@@ -93,7 +93,7 @@ add_task(async function () {
     await TestUtils.waitForCondition(
       () => !syncManager.isOtherInstanceRunning(),
       "waiting for child process to release the lock"
-    ).catch(e => {
+    ).catch(_e => {
       Assert.ok(
         !syncManager.isOtherInstanceRunning(),
         "child process has released the lock"
diff --git a/toolkit/mozapps/update/tests/unit_background_update/test_backgroundupdate_glean.js b/toolkit/mozapps/update/tests/unit_background_update/test_backgroundupdate_glean.js
index 0d9c06b2d0..0ca74e4764 100644
--- a/toolkit/mozapps/update/tests/unit_background_update/test_backgroundupdate_glean.js
+++ b/toolkit/mozapps/update/tests/unit_background_update/test_backgroundupdate_glean.js
@@ -140,7 +140,7 @@ async function do_readTargeting(content, beforeNextSubmitCallback) {
 
 // Missing targeting is anticipated.
 add_task(async function test_targeting_missing() {
-  await do_readTargeting(null, reason => {
+  await do_readTargeting(null, _reason => {
     Assert.equal(false, Glean.backgroundUpdate.targetingExists.testGetValue());
 
     Assert.equal(
@@ -152,7 +152,7 @@ add_task(async function test_targeting_missing() {
 
 // Malformed JSON yields an exception.
 add_task(async function test_targeting_exception() {
-  await do_readTargeting("{", reason => {
+  await do_readTargeting("{", _reason => {
     Assert.equal(false, Glean.backgroundUpdate.targetingExists.testGetValue());
 
     Assert.equal(
@@ -193,7 +193,7 @@ add_task(async function test_targeting_exists() {
     targets: [manager.createTargetingContext(), target],
   });
 
-  await do_readTargeting(JSON.stringify(targetSnapshot), reason => {
+  await do_readTargeting(JSON.stringify(targetSnapshot), _reason => {
     Assert.equal(true, Glean.backgroundUpdate.targetingExists.testGetValue());
 
     Assert.equal(
diff --git a/toolkit/mozapps/update/updater/updater.cpp b/toolkit/mozapps/update/updater/updater.cpp
index 947e84aac3..6b01450b31 100644
--- a/toolkit/mozapps/update/updater/updater.cpp
+++ b/toolkit/mozapps/update/updater/updater.cpp
@@ -3734,7 +3734,7 @@ int NS_main(int argc, NS_tchar** argv) {
           }
           // Set an error so we don't get into an update loop when the callback
           // runs. This will be reset to pending by handleUpdateFailure in
-          // UpdateService.jsm.
+          // UpdateService.sys.mjs.
           WriteStatusFile(SILENT_UPDATE_NEEDED_ELEVATION_ERROR);
           LOG(("Skipping update to avoid UAC prompt from background task."));
           output_finish();