Disruption with some GitHub services

Summary

Disruption with some GitHub services

On May 26, 2026, between 15:10 UTC and 16:35 UTC the Copilot service was degraded and many models were no longer available for use. On average, the error rate was ~5% and peaked at 11% of requests to the service. This was due to a change that introduced a configuration mismatch in HMAC signing credentials which caused the list of available models to be truncated. This was mitigated by rolling back the change. This rollback was complete by 15:34 UTC though users continued to see impact until cache TTLs expired. <br /><br />We are working to improve our monitoring and error handling to reduce time to detection and better experience for issues like this in the future.

• Started

  May 26, 2026 · 3:44 PM

• Resolved

  May 26, 2026 · 4:35 PM

• Duration

  51m

• Severity

  Minor

• ◐

  Investigating

  May 26 · 3:44 PM GitHub

  We are investigating reports of impacted performance for some GitHub services.

• ◐

  Investigating

  May 26 · 3:48 PM GitHub

  Copilot is experiencing degraded performance. We are continuing to investigate.

• ◉

  Monitoring

  May 26 · 4:24 PM GitHub

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

• ✓

  Resolved

  May 26 · 4:35 PM GitHub

  On May 26, 2026, between 15:10 UTC and 16:35 UTC the Copilot service was degraded and many models were no longer available for use. On average, the error rate was ~5% and peaked at 11% of requests to the service. This was due to a change that introduced a configuration mismatch in HMAC signing credentials which caused the list of available models to be truncated. This was mitigated by rolling back the change. This rollback was complete by 15:34 UTC though users continued to see impact until cache TTLs expired. <br /><br />We are working to improve our monitoring and error handling to reduce time to detection and better experience for issues like this in the future.