Resumo
On February 27, 2026, between 22:53 UTC and 23:46 UTC, the Copilot coding agent service experienced elevated errors and degraded functionality for agent sessions. Approximately 87% of attempts to start or interact with agent sessions encountered errors during this period.
This was due to an expired authentication credential for an internal service component, which prevented Copilot agent session operations from completing successfully.
We mitigated the incident by rotating the expired credential and deploying the updated configuration to production. Services began recovering within minutes of the fix being deployed.
We are working to improve automated credential rotation coverage across all Copilot service components, add proactive alerting for credentials approaching expiration, and validate configuration consistency to reduce our time to detection and mitigation of issues like this one in the future.