# Intermittent error spikes for Claude Mythos 5.1 and Claude Fable 5.1

- Provider: [Anthropic](https://down.guide/anthropic)
- Level: confirmed
- Impact: Partial outage
- lasted 1h 26m
- started 2026-09-15 09:48 UTC
- claude.ai, Claude API (api.anthropic.com), Claude Code +1
- id: DWN-92ddc62243
- Official page: https://stspg.io/x1qpycpg6ln7

## Updates from Anthropic
### 2026-09-15 09:48 UTC: investigating
We are investigating elevated errors on requests to Claude Mythos 5.1 and Claude Fable 5.1. We will provide an update as soon as possible.

### 2026-09-15 09:52 UTC: investigating
We are investigating elevated errors on requests to Claude Mythos 5.1 and Claude Fable 5.1. We will provide an update as soon as possible.

### 2026-09-15 10:50 UTC: monitoring
A fix has been deployed for Claude Mythos 5.1 and Claude Fable 5.1 and we are monitoring to ensure it has resolved the issue.

### 2026-09-15 11:14 UTC: resolved
A fix has been deployed for Claude Mythos 5.1 and Claude Fable 5.1 and we are monitoring to ensure it has resolved the issue.

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