Claude outage – Resolved

The outage began around 13:26 UTC on September 3, 2026, when Anthropic reported investigating elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5. At 13:41 UTC, the root cause was identified, and the affected model list expanded to include Mythos/Fable 5, Opus 4.8, and Opus 4.6. By 15:25 UTC, most models had recovered to baseline error rates, with only Opus 4.8 and Opus 5 still affected.

A fix was deployed at 16:06 UTC, after which Anthropic monitored for recovery. Impact officially ended at 9:16 PT / 16:16 UTC, and the incident was marked resolved at 16:23 UTC. The outage affected claude.ai, the Claude API (api.anthropic.com), Claude Code, and Claude Cowork.