[CI Postmortem] Flaky: TestNSUrlSessionEphemeralHandlerCookies on iOS/MacCatalyst

[rolfbjarne]

Flaky Test Report (automated)

Test: MonoTests.System.Net.Http.MessageHandlerTest.TestNSUrlSessionEphemeralHandlerCookies
Platforms: iOS, MacCatalyst
Period: May 4–11, 2026
Category: Flaky (cross-PR, different bots)

Occurrence Summary

PR	Build	Bot	Direct Link
#25340	14024333	VSCXSDKs-MINI-062	Run tests
#25357	14036519	MACIOSMINI-010	Run tests
#25331	14019009	VSCXSDKs-MINI-023	Run tests
#25331	14016858	VSCXSDKs-MINI-005	Run tests
#25320	14017122	VSCXSDKs-MINI-038	Run tests
#25300	14005331	VSCXSDKs-MINI-087	Run tests
#24228	14036449	VSCXSDKs-MINI-023	Run tests

Total: Failed in 7 builds across 6 unrelated PRs

Error Details

  Managed Cookie Value
  Expected: True
  But was:  False

Classification

This failure was identified as flaky because:

• It appeared across 6 unrelated PRs
• It occurs on many different bots (no bot-specific pattern)
• The cookie value assertion is timing/network-dependent

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

[rolfbjarne]

CI Post-Mortem Update (May 11–18, 2026)

This flaky cookie test continues to occur. Not reopening since the issue was closed less than 2 weeks ago (May 13).

New Occurrences

PR	Build	Platform	Date
#25318	14086348	MacCatalyst	May 13
#25415	14084375	macOS	May 13
#25360	14106365	iOS	May 15
#25428	14106399	iOS	May 15

Also seeing TestNSUrlSessionDefaultDisableCookie variants on PRs #25428 and #25429.

Error

Managed Cookie Value
Expected: True
But was:  False

Not reopening — the issue was closed on May 13 (less than 2 weeks ago). If this continues appearing next week, will reopen.

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Automated CI post-mortem analysis