Document ASP.NET Core 10.0 breaking change: Exception diagnostics suppression (#47900)

Author: Copilot

docs/core/compatibility/10.0.md

@@ -20,6 +20,7 @@ If you're migrating an app to .NET 10, the breaking changes listed here might af
 | Title | Type of change      | Introduced version |
 |-------|---------------------|--------------------|
 | [Deprecation of WithOpenApi extension method](aspnet-core/10/withopenapi-deprecated.md) | Source incompatible | Preview 7 |
+| [Exception diagnostics suppressed when TryHandleAsync returns true](aspnet-core/10/exception-handler-diagnostics-suppressed.md) | Behavioral change | Preview 7 |
 | [IActionContextAccessor and ActionContextAccessor are obsolete](aspnet-core/10/iactioncontextaccessor-obsolete.md) | Source incompatible/behavioral change | Preview 7 |
 | [IncludeOpenAPIAnalyzers property and MVC API analyzers are deprecated](aspnet-core/10/openapi-analyzers-deprecated.md) | Source incompatible | Preview 7 |
 | [Microsoft.Extensions.ApiDescription.Client package deprecated](aspnet-core/10/apidescription-client-deprecated.md) | Source incompatible | Preview 7 |

docs/core/compatibility/aspnet-core/10/exception-handler-diagnostics-suppressed.md

@@ -0,0 +1,55 @@
+---
+title: "Breaking change: Exception diagnostics are suppressed when IExceptionHandler.TryHandleAsync returns true"
+description: Learn about the breaking change in ASP.NET Core 10 where exception diagnostics are no longer recorded when IExceptionHandler.TryHandleAsync returns true.
+ms.date: 08/08/2025
+---
+
+# Exception diagnostics are suppressed when IExceptionHandler.TryHandleAsync returns true
+
+The ASP.NET Core exception handler middleware no longer records diagnostics for exceptions handled by <xref:Microsoft.AspNetCore.Diagnostics.IExceptionHandler> by default.
+
+## Version introduced
+
+.NET 10 Preview 7
+
+## Previous behavior
+
+Previously, the exception handler middleware recorded diagnostics about exceptions handled by <xref:Microsoft.AspNetCore.Diagnostics.IExceptionHandler>.
+
+The exception diagnostics are:
+
+- Logging `UnhandledException` to <xref:Microsoft.Extensions.Logging.ILogger>.
+- Writing the `Microsoft.AspNetCore.Diagnostics.HandledException` event to <xref:Microsoft.Extensions.Logging.EventSource>.
+- Adding the `error.type` tag to the `http.server.request.duration` metric.
+
+## New behavior
+
+Starting in .NET 10, if <xref:Microsoft.AspNetCore.Diagnostics.IExceptionHandler.TryHandleAsync%2A?displayProperty=nameWithType> returns `true`, then exception diagnostics are no longer recorded by default.
+
+## Type of breaking change
+
+This change is a [behavioral change](../../categories.md#behavioral-change).
+
+## Reason for change
+
+ASP.NET Core users have given feedback that the previous behavior was undesirable. Their <xref:Microsoft.AspNetCore.Diagnostics.IExceptionHandler> implementation reported that the exception was handled, but the error handling middleware still recorded the error in the app's telemetry.
+
+ASP.NET Core now follows the behavior expected by users by suppressing diagnostics when <xref:Microsoft.AspNetCore.Diagnostics.IExceptionHandler> handles the exception. Configuration options are also available to customize exception diagnostics behavior if needed.
+
+## Recommended action
+
+If you want handled exceptions to continue to record telemetry, you can use the new `ExceptionHandlerOptions.SuppressDiagnosticsCallback` option:
+
+```csharp
+app.UseExceptionHandler(new ExceptionHandlerOptions
+{
+    SuppressDiagnosticsCallback = context => false;
+});
+```
+
+The `context` passed to the callback includes information about the exception, the request, and whether the exception was handled. The callback returns `false` to indicate that diagnostics shouldn't be suppressed, thus restoring the previous behavior.
+
+## Affected APIs
+
+- <xref:Microsoft.AspNetCore.Builder.ExceptionHandlerExtensions.UseExceptionHandler%2A?displayProperty=fullName>
+- <xref:Microsoft.AspNetCore.Diagnostics.IExceptionHandler?displayProperty=fullName>

docs/core/compatibility/toc.yml

@@ -12,6 +12,8 @@ items:
             items:
               - name: Deprecation of WithOpenApi extension method
                 href: aspnet-core/10/withopenapi-deprecated.md
+              - name: Exception diagnostics suppressed when TryHandleAsync returns true
+                href: aspnet-core/10/exception-handler-diagnostics-suppressed.md
               - name: IActionContextAccessor and ActionContextAccessor are obsolete
                 href: aspnet-core/10/iactioncontextaccessor-obsolete.md
               - name: IncludeOpenAPIAnalyzers property and MVC API analyzers are deprecated