ACS SDK WinUI3 App crashes randomly in MSVCP140.dll after video call teardown

Hi @Charupak ,

Thanks for sharing the WinDbg details, that mutex lock crash during teardown is a clear sign of a timing or resource cleanup issue in the native media stack after multiple video calls.

Even after moving to SDK 1.15 and the latest VC++ runtime, the most effective thing we've seen in similar cases is strengthening the teardown sequence. Microsoft’s best practices stress the importance of fully disposing all media objects to avoid leaving the native pipeline in a bad state, especially with repeated calls involving video and Teams interop.

Recommendations:
1. Proper Call Teardown and Resource Disposal Microsoft emphasizes cleaning up resources after each call to prevent memory leaks and native state issues:

• Always call HangUpAsync() followed by Dispose() on the Call object.
• Explicitly dispose of video renderers, local/remote video streams, and related views.
• Unsubscribe from events to avoid lingering references.

Example pattern (adapted from ACS samples and best practices):

private async Task SafeTeardown(Call call)
{
    if (call == null) return;
    try
    {
        await call.HangUpAsync(new HangUpOptions { ForEveryone = false });
    }
    catch { /* Expected errors during teardown can be logged */ }
    // Allow time for native media pipeline to drain (recommended for stability)
    await Task.Delay(500); 
    call.Dispose();
    call = null;
}
// Also dispose these when no longer needed
localVideoStream?.Dispose();
remoteVideoRenderer?.Dispose();
localVideoRenderer?.Dispose();

Also make sure you unsubscribe from all call events (StateChanged, RemoteParticipantsUpdated, etc.) before disposing.

If you haven’t already, enable verbose logging with ClientOptions and collect the ACS logs along with a full memory dump the next time it crashes. That will help the team pinpoint the exact object that’s being accessed after free.

Reference:
https://learn.microsoft.com/en-us/azure/communication-services/concepts/best-practices?tabs=windows&pivots=platform-web

Kindly let us know if the above helps or you need further assistance on this issue.

Please "accept" if the information helped you. This will help us and others in the community as well.