System.Net.WebSockets.Client.Tests.CancelTest_HttpClient_Loopback.SendAsync_Cancel_Success failure: Actual Open when System.Threading.Tasks.TaskCanceledException

[elinor-fung]

Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1544883
Build error leg or test failing: System.Net.WebSockets.Client.Tests.CancelTest_HttpClient_Loopback.SendAsync_Cancel_Success
Pull request: #131894

System.Net.WebSockets.Client.Tests.CancelTest_HttpClient_Loopback.SendAsync_Cancel_Success(useSsl: False) [FAIL]
  Actual Open when System.Threading.Tasks.TaskCanceledException: A task was canceled.
     at System.Net.WebSockets.ManagedWebSocket.SendFrameFallbackAsync(MessageOpcode opcode, Boolean endOfMessage, Boolean disableCompression, ReadOnlyMemory`1 payloadBuffer, Task lockTask, CancellationToken cancellationToken) in /_/src/libraries/System.Net.WebSockets/src/System/Net/WebSockets/ManagedWebSocket.cs:line 602
     at System.Net.WebSockets.Client.Tests.ClientWebSocketTestBase.TestCancellation(Func`2 action, Uri server) in /_/src/libraries/System.Net.WebSockets.Client/tests/ClientWebSocketTestBase.cs:line 74
  Stack Trace:
    /_/src/libraries/System.Net.WebSockets.Client/tests/ClientWebSocketTestBase.cs(79,0): at System.Net.WebSockets.Client.Tests.ClientWebSocketTestBase.TestCancellation(Func`2 action, Uri server)
    /_/src/libraries/System.Net.WebSockets.Client/tests/CancelTest.cs(57,0): at System.Net.WebSockets.Client.Tests.CancelTestBase.RunClient_SendAsync_Cancel_Success(Uri server)
    /_/src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeAsyncTaskContinuation.cs(131,0): at System.Runtime.CompilerServices.RuntimeAsyncTaskContinuation.GetResult(Task task, Byte& result)
    /_/src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeAsyncTaskContinuation.cs(114,0): at System.Runtime.CompilerServices.RuntimeAsyncTaskContinuation.GetResult(Byte& returnValue)
    /_/src/libraries/System.Net.WebSockets.Client/tests/LoopbackServer/LoopbackWebSocketServer.cs(40,0): at System.Net.WebSockets.Client.Tests.LoopbackWebSocketServer.<>c__DisplayClass1_0.<RunAsync>b__0(Uri uri)
    /_/src/libraries/Common/tests/System/Threading/Tasks/TaskTimeoutExtensions.cs(119,0): at System.Threading.Tasks.TaskTimeoutExtensions.GetRealException(Task task)
    --- End of stack trace from previous location ---
    /_/src/libraries/Common/tests/System/Threading/Tasks/TaskTimeoutExtensions.cs(89,0): at System.Threading.Tasks.TaskTimeoutExtensions.WhenAllOrAnyFailed(Task[] tasks)
    /_/src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeAsyncTaskContinuation.cs(131,0): at System.Runtime.CompilerServices.RuntimeAsyncTaskContinuation.GetResult(Task task, Byte& result)
    /_/src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeAsyncTaskContinuation.cs(114,0): at System.Runtime.CompilerServices.RuntimeAsyncTaskContinuation.GetResult(Byte& returnValue)
    /_/src/libraries/Common/tests/System/Threading/Tasks/TaskTimeoutExtensions.cs(54,0): at System.Threading.Tasks.TaskTimeoutExtensions.WhenAllOrAnyFailed(Task[] tasks, Int32 millisecondsTimeout)
    /_/src/libraries/System.Net.WebSockets.Client/tests/LoopbackServer/LoopbackWebSocketServer.Http.cs(32,0): at System.Net.WebSockets.Client.Tests.LoopbackWebSocketServer.HttpRunner.RunAsync(Func`2 clientFunc, Func`3 wsServerFunc, Options options, CancellationToken clientExitCt, CancellationToken globalCt)
    --- End of stack trace from previous location ---

Error Message

{
  "ErrorMessage": ["SendAsync_Cancel_Success", "Actual Open when System.Threading.Tasks.TaskCanceledException"],
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1544883
Error message validated: [SendAsync_Cancel_Success Actual Open when System.Threading.Tasks.TaskCanceledException]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 8/8/2026 2:15:59 AM UTC

Report

Build	Repository	Test	Pull Request
1545618	dotnet/runtime	System.Net.WebSockets.Client.Tests.CancelTest_HttpClient_Loopback.SendAsync_Cancel_Success	#132043
1545295	dotnet/runtime	System.Net.WebSockets.Client.Tests.CancelTest_HttpClient_Http2Loopback.SendAsync_Cancel_Success	#132032
1544883	dotnet/runtime	System.Net.WebSockets.Client.Tests.CancelTest_HttpClient_Loopback.SendAsync_Cancel_Success	#131894

Summary

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

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