Claude outage on 27 October 2026
Major outageAn email when it goes down, and when it’s back.
“Elevated errors for Claude Sonnet 5.5”
On 27 October, Claude had a major outage with elevated errors on requests to Claude Sonnet 5.5, affecting claude.ai, the Claude API, Claude Code and Claude Cowork. The incident was open on the status page for 41 minutes, from 15:09 to 15:50 UTC, but the status page's final update said the impact actually ran from 14:42 to 15:17 UTC, before the incident was opened. Blackbaud, OpenAI, Musixmatch, Thomson Reuters Legal and Procore also reported problems around the same time, and this was Claude's fourth outage in four days.
Claude’s own incident page ↗- When
- 15:09–15:50 UTC
- How long
- 41 min
- Incident open on its page
- 15:09–15:50 UTC
- Components affected
- 4
- Claude, 30 days before
- 8 other outages
What broke when
From Claude’s own status page: when it moved each component into trouble, and back.
At the same time
Started in the hour before or during it
And 135 lesser-known services. Problems at the same time are a clue, never proof that one caused another.
Timeline
Times in UTC
- Cause identified
- claude.ai: partial outage
- Claude API (api.anthropic.com): partial outage
- Claude Code: partial outage
- Claude Cowork: partial outage
- Resolved
- claude.ai: back to normal
- Claude API (api.anthropic.com): back to normal
- Claude Code: back to normal
- Claude Cowork: back to normal
Where this comes from
Stackpulse reads Claude’s official status page at status.claude.com every minute. The times above are when it reported the problem; the summary is written from its updates and checked against them.
Stackpulse isn’t affiliated with Claude. Names and logos belong to their owners.