Incident with Pull Requests

Summary

Incident with Pull Requests

On September 20, 2026, between 21:46 and 22:24 UTC the Pull Requests service was degraded and pull request merge and test-merge commits were created late, with delays reaching approximately four minutes at peak. Merge commits were delayed rather than lost. Because some Actions workflow runs start only after a pull request's merge commit is created, a subset of workflow runs for pull request events were also delayed. <br /><br />This was due to a routine repository maintenance job for an unusually large repository consuming nearly all of the memory on a single Git storage server, which left that server unable to serve the Git operations used to create merge commits. <br /><br />We mitigated the incident by removing the affected server from service at 22:18 UTC, after which the queued merge commits were created within six minutes. <br /><br />We have capped the memory a single repository maintenance job may consume so that one repository cannot exhaust a server, and we have improved monitoring and alerting on storage server health to reduce our time to detection and mitigation of issues like this one in the future.

• Started

  Sep 20, 2026 · 10:13 PM

• Resolved

  Sep 20, 2026 · 11:22 PM

• Duration

  1h 8m

• Severity

  Minor

• ◐

  Investigating

  Sep 20 · 10:13 PM GitHub

  We are investigating reports of degraded performance for Pull Requests

• ◉

  Monitoring

  Sep 20 · 10:27 PM GitHub

  The degradation affecting Pull Requests has been mitigated. We are monitoring to ensure stability.

• ◉

  Monitoring

  Sep 20 · 10:32 PM GitHub

  A git fileserver issue caused a brief delay in creating some merge commits - we've isolated the underlying server and already observed recovery.

• ✓

  Resolved

  Sep 20 · 11:22 PM GitHub

  On September 20, 2026, between 21:46 and 22:24 UTC the Pull Requests service was degraded and pull request merge and test-merge commits were created late, with delays reaching approximately four minutes at peak. Merge commits were delayed rather than lost. Because some Actions workflow runs start only after a pull request's merge commit is created, a subset of workflow runs for pull request events were also delayed. <br /><br />This was due to a routine repository maintenance job for an unusually large repository consuming nearly all of the memory on a single Git storage server, which left that server unable to serve the Git operations used to create merge commits. <br /><br />We mitigated the incident by removing the affected server from service at 22:18 UTC, after which the queued merge commits were created within six minutes. <br /><br />We have capped the memory a single repository maintenance job may consume so that one repository cannot exhaust a server, and we have improved monitoring and alerting on storage server health to reduce our time to detection and mitigation of issues like this one in the future.