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

- Impact (vendor’s label): critical
- Status: resolved · edited after publishing
- Started: 2026-10-23 23:39 UTC · Resolved: 2026-10-24 00:11 UTC · Duration: 32 min
- Updates: 4 · Affected components: claude.ai, Claude API - api.anthropic.com, Claude Code, Claude Cowork
- [Vendor status page: https://status.claude.com/incidents/h101vcmhnfky](https://status.claude.com/incidents/h101vcmhnfky)
- [Company: Anthropic](https://rewindex.com/company/anthropic.md)

## Timeline of updates

- **investigating** 2026-10-23 23:37 UTC: We are investigating elevated errors on requests to Claude Fable 5.1. We will provide an update as soon as possible.
- **identified** 2026-10-23 23:39 UTC: 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.
- **monitoring** 2026-10-23 23:54 UTC: We are seeing success rates return to normal for all affected models, and are continuing to monitor to ensure no further issues.
- **resolved** 2026-10-24 00:11 UTC: 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.

## Rewindex changes for this incident

- 2026-10-23 23:39 UTC: [Critical incident: Elevated errors for Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5](https://rewindex.com/change/i735fd0dfe8e3ef.md)
- 2026-10-24 00:04 UTC: [Incident updated: Elevated errors for Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5](https://rewindex.com/change/r922de7a570d14f.md)
- 2026-10-24 00:13 UTC: [Incident updated: Elevated errors for Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5](https://rewindex.com/change/r478a76f29dd22e.md)


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Canonical: https://rewindex.com/company/anthropic/incidents/h101vcmhnfky · Markdown: https://rewindex.com/company/anthropic/incidents/h101vcmhnfky.md · JSON: https://rewindex.com/api/v1/companies/anthropic/incidents/h101vcmhnfky · Generated 2026-10-24T10:20:41.541Z