[CI] Xcode 27 beta 5 Windows integration bots run macOS 26.3.1 instead of 26.4

[dalexsoto]

Summary

Windows Integration Test bot reservation repeatedly selects a macOS 26.3.1 host for Xcode 27 beta 5, but that Xcode build requires macOS 26.4. Provisioning retries four times and fails before Windows integration tests start.

• Stable signature: windows-integration-xcode27-host-macos-too-old
• Classification: CI infrastructure failure
• Distinct monitored PRs: 2
• Confirmed occurrences: 2
• First observed: 2026-08-12 15:14 UTC
• Latest observed: 2026-08-12 16:09 UTC

Confirmed occurrences

• [FSKit] Update bindings up to Xcode 27.0 Beta 5 #26433, head d0131c28fdd6e6107db5df5c7c13a9d613367e5e
  • Build 14949555, Windows Integration Tests / Reserve macOS bot
  • Host: macOS 26.3.1; Xcode 27 beta 5 requirement: macOS 26.4.
  • Four provisioning task attempts failed. The overall build remains active.
• [Bindings] Update multiple frameworks up to Xcode 27.0 Beta 5 #26438, head c12070bcb25ea8e62f8ed751289073f3bbb2d32b
  • Build 14949997, Windows Integration Tests / Reserve macOS bot
  • Host: macOS 26.3.1; Xcode 27 beta 5 requirement: macOS 26.4.
  • Four provisioning task attempts failed. The overall build remains active.

Reproduction and impact

The failure occurs before test execution while expanding and validating Xcode_27_beta_5.xip. Reserving an incompatible host deterministically fails the Windows Integration stage.

Investigation performed

Azure build metadata, timelines, and provisioning task logs were inspected for both runs. Separate open/closed issue searches used the Xcode version, required/actual macOS versions, provisioning task, and Windows Integration component strings; no matching issue was found.

Retry status and workaround

No retry has been submitted yet because both builds are still active. Under repository policy, the entire Windows Integration Tests stage must be rerun after terminal status, conflict/head/budget reconciliation, and confirmation that no equivalent retry is active. Infrastructure should reserve a macOS 26.4-or-newer host for Xcode 27 beta 5.

[dalexsoto]

Retry update for #26438 at c12070bcb25ea8e62f8ed751289073f3bbb2d32b:

• Azure accepted an external retry of the entire Windows Integration Tests stage in build 14949997.
• Stage attempt 2 (ca80badf-8fec-5655-1b76-616243af72c4) and Reserve macOS bot for tests attempt 2 are currently in progress.
• The initiating actor is unavailable from retained Azure/GitHub metadata.
• Retry accounting is 2 PR-lifetime / 1 current-head retry, including the superseded old-head simulator retry.

No equivalent additional retry will be submitted while this stage attempt is active.

[dalexsoto]

Retry progress for #26438 at c12070bcb25ea8e62f8ed751289073f3bbb2d32b:

• Windows Integration stage attempt 2 successfully completed Reserve macOS bot for tests (job 2557785c-4529-5de2-77ee-d3d21d31a53a).
• The Dotnet tests phase is now in progress, confirming the Xcode/macOS host compatibility failure did not recur on the replacement bot.
• Retry accounting remains 2 PR-lifetime / 1 current-head retry.

The stage remains active; final outcome will be reported when terminal.

[dalexsoto]

Retry update for #26433 at d0131c28fdd6e6107db5df5c7c13a9d613367e5e:

• Azure accepted a monitor-initiated retry through the API for build 14949555.
• The entire Windows Integration Tests stage is running as attempt 2 (ca80badf-8fec-5655-1b76-616243af72c4), with bot reservation pending.
• The same request reruns the separate T: monotouch_ios failure.
• Retry accounting is 8 PR-lifetime / 8 current-head requests. No equivalent retry will be submitted while attempt 2 is active.

[dalexsoto]

Retry outcome for #26433 at d0131c28fdd6e6107db5df5c7c13a9d613367e5e:

• Build 14949555, Windows Integration stage attempt 2 reproduced the host incompatibility.
• The replacement bot again runs macOS 26.3.1 while Xcode 27 beta 5 requires 26.4; all four provisioning task attempts failed.
• The shared retry request remains active because the separate T: monotouch_ios/publish work has not finished. No additional equivalent retry will be submitted meanwhile.
• Retry accounting remains 8 PR-lifetime / 8 current-head requests.

The recurrence remains 2 distinct PRs, now with 3 confirmed stage occurrences.

[dalexsoto]

Terminal retry outcome for #26438 at c12070bcb25ea8e62f8ed751289073f3bbb2d32b:

• Build 14949997, Windows Integration stage attempt 2 completed successfully.
• The replacement bot passed reservation, Dotnet tests, result publication, and cleanup; the macOS 26.3.1/Xcode 27 beta 5 incompatibility did not recur.
• Retry accounting remains 2 PR-lifetime / 1 current-head accepted retry.

The overall simulator build still failed only because of the separately tracked T: monotouch_ios startup timeout; that does not change this Windows infrastructure retry outcome.