Is it safe to ignore the warning about <AllowUnsafeBlocks>true</AllowUnsafeBlocks>

Hi @Hong ,

I recommend adding AllowUnsafeBlocks=true to the project that reports this warning. The warning does not, by itself, mean that your app is currently failing, but the fact that the Debug, Release, and Store versions run successfully is not enough to conclude that it is always safe to ignore.

Your screenshot shows CsWinRT1030 for Task<Microsoft.UI.Xaml.Controls.ContentDialogResult>, the task returned by AsTask(). This is a C#/WinRT compatibility diagnostic concerning managed types that may be passed to Windows Runtime APIs. It does not establish that the returned task actually crosses that boundary in your code.

In a local .NET 8 build using Windows App SDK 1.7.250909003, I reproduced the same diagnostic when returning that result as the base Task type. Setting AllowUnsafeBlocks=true removed the warning. This was a build comparison, not a reproduction of a runtime failure in your application.

Microsoft's C#/WinRT documentation explains that its reflection-based support remains available for applications without trimming or Native AOT. For those builds, this warning does not automatically imply a runtime problem. If the relevant object crosses the WinRT boundary in a trimmed or Native AOT build, compatible interop code is needed, and ignoring compatibility diagnostics can leave runtime issues undiscovered. The effective PublishTrimmed and PublishAot settings matter here; the configuration name or Store packaging alone does not determine them.

Add this inside the affected .csproj file:

<PropertyGroup>
  <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
</PropertyGroup>

As documented under AllowUnsafeBlocks, this permits code explicitly marked unsafe to compile, including generated interop code. It does not automatically make all your existing C# code unsafe or enable trimming or Native AOT.

After rebuilding, check that CsWinRT1030 is gone, then create a fresh Release package and exercise the dialog operation. If you prefer to leave the setting disabled, please share the code around this AsTask() call and the effective PublishTrimmed and PublishAot values for your published build. Those details would help determine whether this particular warning can be disregarded in your app.

If you have any problems or questions, feel free to ask or leave a comment, I will responses as soon as possible.

Thank you.