Breaking change docs: IHost.RunAsync/StopAsync throw when BackgroundService fails (.NET 11)

[Copilot]

In .NET 11 Preview 3, when a BackgroundService.ExecuteAsync throws and BackgroundServiceExceptionBehavior is StopHost (default), the host-level async methods now propagate the exception instead of completing successfully—causing a non-zero exit code.

Changes

• New article: docs/core/compatibility/extensions/11.0/ihost-runasync-stopasync-throw-backgroundservice-failure.md
  • Documents previous behavior (silent success), new behavior (exception propagation + AggregateException for multiple failures), reason (hiding failures was wrong), and migration path
• 11.md: Added Extensions section (alphabetical order) referencing the new article
• toc.yml: Added .NET 11 > Extensions entry

Recommended action from the article

Do nothing—non-zero exit on failure is correct. To preserve the old success-exit behavior:

try
{
    await host.RunAsync();
}
catch (Exception ex)
{
    // Log or inspect the exception if needed.
}

Affected APIs

HostingAbstractionsHostExtensions.RunAsync/Run/StopAsync/WaitForShutdownAsync/WaitForShutdown and the default IHost.StopAsync implementation.

---

Internal previews

📄 File	🔗 Preview link
docs/core/compatibility/11.md	docs/core/compatibility/11
docs/core/compatibility/extensions/11.0/ihost-runasync-stopasync-throw-backgroundservice-failure.md	docs/core/compatibility/extensions/11.0/ihost-runasync-stopasync-throw-backgroundservice-failure
docs/core/compatibility/toc.yml	docs/core/compatibility/toc

[Copilot]

Pull request overview

Adds a new .NET 11 breaking change article under the Extensions area describing exception propagation from host-level run/stop/wait APIs when a BackgroundService fails, and wires the article into the .NET 11 breaking-change index and TOC.

Changes:

• Adds a new breaking change article documenting updated exception/exit-code behavior for IHost run/stop/wait APIs when BackgroundService.ExecuteAsync throws.
• Adds an Extensions section to the .NET 11 breaking changes index page and links the new article.
• Updates the compatibility TOC to include the new .NET 11 Extensions node and article link.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
docs/core/compatibility/toc.yml	Adds a .NET 11 Extensions TOC node pointing to the new breaking change article.
docs/core/compatibility/extensions/11.0/ihost-runasync-stopasync-throw-backgroundservice-failure.md	New breaking change article documenting the behavior change, rationale, recommended action, and affected APIs.
docs/core/compatibility/11.md	Adds an Extensions section and links the new breaking change article.