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.
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.
Posted May 26, 2026 - 16:35 UTC
Monitoring
The degradation affecting Copilot has been mitigated. We are monitoring to ensure stability.
Posted May 26, 2026 - 16:24 UTC
Update
Copilot is experiencing degraded performance. We are continuing to investigate.
Posted May 26, 2026 - 15:48 UTC
Investigating
We are investigating reports of impacted performance for some GitHub services.
