[ci-scan] Test failure: System.Net.Security.Tests.SslStreamTlsResumeTests.ClientDisableTlsResume_Succeeds

Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1600102 Build error leg or test failing: windows-x86 Debug Libraries_CheckedCoreCLR - windows.10.amd64.open.rt - System.Net.Security.Tests Pull request: https://github.com/dotnet/runtime/pull/133932

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Error Details

System.Net.Security.Tests.SslStreamTlsResumeTests.ClientDisableTlsResume_Succeeds(testClient: False) [FAIL]
  Assert.True() Failure
  Expected: True
  Actual:   False
  Stack Trace:
    /_/src/libraries/System.Net.Security/tests/FunctionalTests/SslStreamAllowTlsResumeTests.cs(134,0): at System.Net.Security.Tests.SslStreamTlsResumeTests.ClientDisableTlsResume_Succeeds(Boolean testClient)
    --- End of stack trace from previous location ---

This is a post-fix recurrence of #103449 after #126693 merged on April 14, 2026. The current failure occurred in a build completed on September 17, 2026 and affects the testClient: False path after TLS resumption is re-enabled on the server side.

Error Message

{
  "ErrorMessage": [
    "System.Net.Security.Tests.SslStreamTlsResumeTests.ClientDisableTlsResume_Succeeds(testClient: False) [FAIL]",
    "/_/src/libraries/System.Net.Security/tests/FunctionalTests/SslStreamAllowTlsResumeTests.cs(134,0): at System.Net.Security.Tests.SslStreamTlsResumeTests.ClientDisableTlsResume_Succeeds(Boolean testClient)"
  ],
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Workflow artifact: ci-failure-scan Artifact kind: kbe-verification Verified match count: 1 hits in failure.log

[!NOTE] This issue was created with GitHub Copilot assistance.

Known issue validation

Build: :mag_right: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1600102 Error message validated: [System.Net.Security.Tests.SslStreamTlsResumeTests.ClientDisableTlsResume_Succeeds(testClient: False) [FAIL] /_/src/libraries/System.Net.Security/tests/FunctionalTests/SslStreamAllowTlsResumeTests.cs(134,0): at System.Net.Security.Tests.SslStreamTlsResumeTests.ClientDisableTlsResume_Succeeds(Boolean testClient)] Result validation: :white_check_mark: Known issue matched with the provided build. Validation performed at: 9/17/2026 2:02:31 AM UTC

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