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

- Provider: [Anthropic](https://down.guide/anthropic)
- Level: confirmed
- Impact: Major outage
- lasted 34m
- started 2026-10-23 23:37 UTC
- claude.ai, Claude API (api.anthropic.com), Claude Code +1
- id: DWN-e6ab419d78
- Official page: https://stspg.io/gqp288t3qzpt

## Root cause
> We have identified the cause of elevated errors on requests to Claude Fable 5.

[Postmortem](https://stspg.io/gqp288t3qzpt)

## Updates from Anthropic
### 2026-10-23 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.

### 2026-10-23 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.

### 2026-10-23 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.

### 2026-10-24 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.

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