Critical incident

Anthropic (Claude): Elevated errors for Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5

Affected: claude.ai, Claude API (api.anthropic.com), Claude Code, Claude Cowork

Current status of Anthropic (Claude): Operational — live Anthropic (Claude) status

Timeline

1. Oct 23, 2026, 23:37 UTC
   investigating
   We are investigating elevated errors on requests to Claude Fable 5.1. We will provide an update as soon as possible.
2. Oct 23, 2026, 23:39 UTC
   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.
3. Oct 23, 2026, 23:54 UTC
   monitoring
   We are seeing success rates return to normal for all affected models, and are continuing to monitor to ensure no further issues.
4. Oct 24, 2026, 00:11 UTC
   resolved
   The issue affecting Claude models has been resolved. Impact occurred from 16:28 PT / 23:28 UTC on October 23 to 16:59 PT / 23:59 UTC on October 23.

Updates as published by Anthropic (Claude) (original).