Incident report · read from Anthropic's status page

Anthropic incident: Elevated errors for Claude Sonnet 5.5 and other models

Resolved after 1 h 39 m (25 Oct 2026, 06:14–07:53 UTC), impact major, affecting Claude Cowork, Claude API (api.anthropic.com), claude.ai and Claude Code.

Timeline

1. 25 Oct 2026 at 06:14 UTC investigating

   We are investigating elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5. We will provide an update as soon as possible.

2. 25 Oct 2026 at 06:27 UTC identified

   We have identified the cause of elevated errors on requests to Claude Sonnet 5.5 and are working on a fix. We will provide an update as soon as possible.

3. 25 Oct 2026 at 06:35 UTC monitoring

   A fix has been deployed for the issue affecting Claude services and we are monitoring for recovery.

4. 25 Oct 2026 at 07:53 UTC resolved

   The issue affecting Claude services has been resolved. Impact occurred from 23:05 PT on October 24 / 06:05 UTC on October 25 to 23:35 PT on October 24 / 06:35 UTC on October 25.

Affected components

• Claude Cowork: partial outage for 21 m
• Claude API (api.anthropic.com): partial outage for 21 m
• claude.ai: partial outage for 21 m
• Claude Code: partial outage for 21 m

What the crowd did

• 0 clicks, 2 zombies at their worst, 5 breaches, over 1 h 41 m — 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 30 Oct 2026 at 15:36 UTC.

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