Discussion Hub for new Claude incident: Elevated errors for multiple models on Sep 22, 2026

On September 22, 2026, Claude experienced elevated errors across multiple models. The incident, which occurred from 5:50 PM PT / 00:50 UTC to 7:10 PM PT / 02:10 UTC, initially affected Claude Fable 5, 5.1, Mythos 5, and 5.1, which later returned to normal success rates. Efforts continued to resolve issues impacting Claude Opus 5. The incident was officially resolved by 02:35 UTC.

This report uniquely tracks the incident's progression from initial elevated errors across multiple Claude models to the resolution of specific models like Fable and Mythos, unlike general status updates.