Incident report · read from Anthropic's status page

Anthropic incident: Elevated errors for multiple models

Resolved after 2 h 57 m (3 Sep 2026, 13:26–16:23 UTC), impact major, affecting Claude Cowork, Claude API (api.anthropic.com), claude.ai and Claude Code.

Timeline

3 Sep 2026 at 13:26 UTC investigating
We are investigating elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5. We will provide an update as soon as possible.
3 Sep 2026 at 13:41 UTC identified
We have identified the cause of elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 and are working on a fix. We will provide an update as soon as possible.
3 Sep 2026 at 13:50 UTC identified
An exhaustive list of affected models: Mythos/Fable 5.1, Mythos/Fable 5, Opus 5, Opus 4.8, Opus 4.6.
3 Sep 2026 at 14:49 UTC identified
We are continuing to work on a fix for this issue.
3 Sep 2026 at 15:25 UTC identified
The only affected models right now are Opus 4.8 and Opus 5. The rest of the models have recovered to baseline error rate.
3 Sep 2026 at 16:06 UTC monitoring
A fix has been deployed for Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 and we are monitoring for recovery.
3 Sep 2026 at 16:23 UTC resolved
The issue affecting Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 has been resolved. Impact has ended as of 9:16 PT / 16:16 UTC.

Affected components

Claude Cowork: partial outage for 2 h 57 m
Claude API (api.anthropic.com): partial outage for 2 h 57 m
claude.ai: partial outage for 2 h 57 m
Claude Code: partial outage for 2 h 57 m

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 8 Sep 2026 at 15:01 UTC.

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