System.Net.WebSockets.Client.Tests: Assertion failed: !_hasWaiter

[jkotas]

Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1187767
Build error leg or test failing: System.Net.WebSockets.Client.Tests.WorkItemExecution
Pull request: #121139

Error Message

Fill the error message using step by step known issues guidance.

{
  "ErrorMessage": ["Assertion failed.","!_hasWaiter"],
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1187767
Error message validated: [Assertion failed. !_hasWaiter]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 10/29/2025 3:09:07 AM UTC

Report

Build	Definition	Test	Pull Request
1279251	dotnet/runtime	System.Net.WebSockets.Client.Tests.WorkItemExecution	#122722
1278517	dotnet/runtime	System.Net.WebSockets.Client.Tests.WorkItemExecution	#123734
1275628	dotnet/runtime	System.Net.WebSockets.Client.Tests.WorkItemExecution	#123845

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
0	0	3

[jkotas]

Full stacktrace:

Process terminated.
Assertion failed.
!_hasWaiter
   at System.Net.Http.Http2Connection.Http2Stream.TryReadFromBuffer(Span`1 buffer, Boolean partOfSyncRead) in /_/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http2Stream.cs:line 1129
   at System.Net.Http.Http2Connection.Http2Stream.ReadDataAsync(Memory`1 buffer, HttpResponseMessage responseMessage, CancellationToken cancellationToken) in /_/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http2Stream.cs:line 1164
   at System.Net.Http.Http2Connection.Http2Stream.ReadDataAsync(Memory`1 buffer, HttpResponseMessage responseMessage, CancellationToken cancellationToken)
   at System.Net.Http.Http2Connection.Http2Stream.Http2ReadWriteStream.ReadAsync(Memory`1 destination, CancellationToken cancellationToken) in /_/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http2Stream.cs:line 1619
   at System.Net.WebSockets.ManagedWebSocket.WaitForServerToCloseConnectionAsync(CancellationToken cancellationToken) in /_/src/libraries/System.Net.WebSockets/src/System/Net/WebSockets/ManagedWebSocket.cs:line 1134
   at System.Net.WebSockets.ManagedWebSocket.WaitForServerToCloseConnectionAsync(CancellationToken cancellationToken)
   at System.Net.WebSockets.ManagedWebSocket.SendCloseFrameAsync(WebSocketCloseStatus closeStatus, String closeStatusDescription, CancellationToken cancellationToken) in /_/src/libraries/System.Net.WebSockets/src/System/Net/WebSockets/ManagedWebSocket.cs:line 1560
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) in /_/src/libraries/System.Private.CoreLib/src/System/Threading/ExecutionContext.cs:line 179
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext() in /_/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncTaskMethodBuilderT.cs:line 350
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining) in /_/src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/TaskContinuation.cs:line 795
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject) in /_/src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs:line 3475
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result) in /_/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncTaskMethodBuilderT.cs:line 494
   at System.Net.WebSockets.ManagedWebSocket.WaitForWriteTaskAsync(ValueTask writeTask, Boolean shouldFlush) in /_/src/libraries/System.Net.WebSockets/src/System/Net/WebSockets/ManagedWebSocket.cs:line 591
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state) in /_/src/libraries/System.Private.CoreLib/src/System/Threading/ExecutionContext.cs:line 264
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread) in /_/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncTaskMethodBuilderT.cs:line 354
   at System.Threading.ThreadPoolWorkQueue.Dispatch() in /_/src/libraries/System.Private.CoreLib/src/System/Threading/ThreadPoolWorkQueue.cs:line 1154
   at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart() in /_/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.WorkerThread.cs:line 118
   at System.Threading.Thread.StartCallback() in /_/src/coreclr/System.Private.CoreLib/src/System/Threading/Thread.CoreCLR.cs:line 106

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[CarnaViire]

Triage:
Likely related to #117267. We should investigate in 11.0