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diff --git a/compiler/rustc_error_codes/src/error_codes/E0203.md b/compiler/rustc_error_codes/src/error_codes/E0203.md
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+Having multiple relaxed default bounds is unsupported.
+
+Erroneous code example:
+
+```compile_fail,E0203
+struct Bad<T: ?Sized + ?Send>{
+    inner: T
+}
+```
+
+Here the type `T` cannot have a relaxed bound for multiple default traits
+(`Sized` and `Send`). This can be fixed by only using one relaxed bound.
+
+```
+struct Good<T: ?Sized>{
+    inner: T
+}
+```