Incident report · read from Anthropic's status page
Anthropic incident: Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1
Resolved after 17 m (11 Sep 2026, 14:19–14:37 UTC), impact major, affecting Claude Cowork, Claude API (api.anthropic.com), claude.ai and Claude Code.
Timeline
- investigating
We are investigating elevated errors on requests to Claude Fable 5.1 and Claude Mythos 5.1. We will provide an update as soon as possible.
- identified
We have identified the cause of elevated errors on requests to Claude Mythos 5.1 and Claude Fable 5.1 and are working on a fix. We will provide an update as soon as possible.
- monitoring
A fix has been deployed for Claude Mythos 5.1 and Claude Fable 5.1 and we are monitoring for recovery.
- monitoring
A fix has been deployed for the issue affecting Claude services and we are monitoring for recovery.
- resolved
The issue affecting Claude services has been resolved. Impact occurred from 13:57 to 14:20 UTC
Affected components
- Claude Cowork: partial outage for 17 m
- Claude API (api.anthropic.com): partial outage for 8 m
- claude.ai: partial outage for 8 m
- Claude Code: partial outage for 8 m
What the crowd did
- 1 037 clicks, 40 zombies at their worst, 759 breaches, over 1 d 2 h — the siege in full
That is this site's own record of the crowd at Anthropic's gate, not anything Anthropic published.
Source
Anthropic's own report of this incident, on Anthropic's status page. This page is a record of Anthropic's own report; where the two disagree, theirs is right.
Last checked .
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