[CI] Flaky: NSUrlSessionHandlerTest.BasicAuthWorksWhenBearerIsAdvertisedFirst on macOS

[rolfbjarne]

Flaky Test Report (automated)

Test: MonoTests.System.Net.Http.NSUrlSessionHandlerTest.BasicAuthWorksWhenBearerIsAdvertisedFirst
Platform: macOS
Category: Flaky
Period: May 25 – Jun 1, 2026

Occurrence Summary

PR	Build	Bot	Config
#25527	14219070	VSCXSDKs-MINI-015.Tahoe.arm64	Debug (static registrar)
#25564	14230377	VSCXSDKs-MINI-015.Tahoe.arm64	Debug (static registrar)
#25568	14242688	VSCXSDKs-MINI-015.Tahoe.arm64	Debug (static registrar)

Total: Failed in 3 builds across 3 unrelated PRs.

Error Details

MonoTests.System.Net.Http.NSUrlSessionHandlerTest.BasicAuthWorksWhenBearerIsAdvertisedFirst
  Expected 200 OK after Basic auth negotiation
  Expected: OK
  But was:  NotFound

Classification

This failure was identified as flaky because:

• It appeared across 3 unrelated PRs (different authors, different changes)
• The PRs do not modify networking or HTTP handler code
• The test involves network communication which is inherently timing-sensitive

Notes

• All 3 occurrences are in the macOS Debug (static registrar) configuration
• All ran on the same bot (VSCXSDKs-MINI-015) — this may be a bot-specific network issue
• PR [tests] Improve new BasicAuthWorksWhenBearerIsAdvertisedFirst test. #25503 previously attempted to improve this test's reliability

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This issue was automatically generated by CI post-mortem analysis.