Some macOS Actions jobs routing to Ubuntu instead
This summary is created by Generative AI and may differ from the actual content.
Overview
Some macOS Actions jobs were routed to Ubuntu instead of MacOS between December 9th, 2025 21:07 UTC and December 10th, 2025 14:52 UTC, impacting 177 macos-14-large jobs.
Impact
177 macos-14-large jobs were run on an Ubuntu larger runner VM instead of MacOS runner VMs.
Trigger
A manual override was done previously for internal testing, but left incorrect metadata for a large runner instance, which was brought online by an infrastructure migration.
Detection
The exact method of detection is not specified in the postmortem.
Resolution
The mitigation involved deleting the runner and ensuring all macOS jobs route to macOS fulfillers.
Root Cause
The root cause was a misconfigured runner due to a manual override left after internal testing, which was brought online by an infrastructure migration.