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

- Provider: [Anthropic](https://outages.cc/anthropic.md)
- Type: Incident
- State: Resolved
- Worst impact: Partial outage
- Started: 2026-09-15 09:48 UTC
- Resolved: 2026-09-15 11:14 UTC (lasted 1 h 26 min)
- Components: claude.ai, Claude API (api.anthropic.com), Claude Code, Claude Cowork
- Official update: https://stspg.io/x1qpycpg6ln7

## Updates from Anthropic

### resolved, 2026-09-15 11:14 UTC

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.

### monitoring, 2026-09-15 10:50 UTC

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.

### investigating, 2026-09-15 09:52 UTC

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.

### investigating, 2026-09-15 09:48 UTC

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.