GitHub outage on 2026-08-13: Errors with the Fable 5 Model in Copilot

On August 13th, 2026, between approximately 14:06 and 15:47 UTC, the Copilot service experienced a degradation of the Claude Fable 5 model due to an issue with our upstream provider. Users encountered elevated error rates, peaking at 43% and averaging 12%. Users who selected Auto or alternative models were unaffected.<br /><br />The issue was resolved by a mitigation put in place by our provider. GitHub is working with our provider to further improve the resiliency of the service to prevent similar incidents in the future.