On November 28th, 2025, between approximately 05:51 and 08:04 UTC, Copilot experienced an outage affecting the Claude Sonnet 4.5 model. Users attempting to use this model received an HTTP 400 error, resulting in 4.6% of total chat requests during this timeframe failing. Other models were not impacted.
The issue was caused by a misconfiguration deployed to an internal service which made Claude Sonnet 4.5 unavailable. The problem was identified and mitigated by reverting the change. GitHub is working to improve cross-service deploy safeguards and monitoring to prevent similar incidents in the future.
Posted Nov 28, 2025 - 08:23 UTC
Update
We have rolled out a fix and are monitoring for recovery.
Posted Nov 28, 2025 - 07:52 UTC
Update
We are investigating degraded performance with the Claude Sonnet 4.5 model in Copilot.
Posted Nov 28, 2025 - 07:04 UTC
Investigating
We are investigating reports of degraded performance for Copilot
