Anthropic API outage on 23 October 2026

Status	Resolved
Worst verdict	Likely down
Started	23 Oct 2026, 23:38 UTC
Ended	24 Oct 2026, 00:12 UTC
Duration	34 min
Official incident	Elevated errors for Claude Fable 5.1
Affected	Claude API (api.anthropic.com), claude.ai, Claude Code, Claude Cowork

Timeline

23 Oct 2026, 23:38 UTC

We started seeing problems. Our verdict: Likely down.
23 Oct 2026, 23:38 UTC · official update

Elevated errors for Claude Fable 5.1 (investigating): “We are investigating elevated errors on requests to Claude Fable 5.1. We will provide an update as soon as possible.” Source
23 Oct 2026, 23:39 UTC · official update

Elevated errors for Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5 (identified): “We have identified the cause of elevated errors on requests to Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5, as well as fast mode requests to Opus 5.5 and are working on a fix. We will provide an update as soon as possible.” Source
23 Oct 2026, 23:54 UTC · official update

Elevated errors for Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5 (monitoring): “We are seeing success rates return to normal for all affected models, and are continuing to monitor to ensure no further issues.” Source
24 Oct 2026, 00:12 UTC

Looking normal again. We'll keep watching for 15 minutes before closing this.
24 Oct 2026, 00:26 UTC

Everything has looked normal for 15 minutes, so we marked this incident as resolved.

Times are shown in your local time zone. “Official update” entries quote Anthropic's status page; follow the source link for the full text.

How we track incidents

We open an incident when Anthropic API stops looking normal or Anthropic posts an official incident, and close it after 15 minutes with everything back to normal. More about our method.