Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1

Incident Report for Claude

Resolved

The issue affecting Claude services has been resolved. Impact occurred from 13:57 to 14:20 UTC
Posted Sep 11, 2026 - 14:37 UTC

Update

A fix has been deployed for the issue affecting Claude services and we are monitoring for recovery.
Posted Sep 11, 2026 - 14:28 UTC

Monitoring

A fix has been deployed for Claude Mythos 5.1 and Claude Fable 5.1 and we are monitoring for recovery.
Posted Sep 11, 2026 - 14:28 UTC

Identified

We have identified the cause of elevated errors on requests to Claude Mythos 5.1 and Claude Fable 5.1 and are working on a fix. We will provide an update as soon as possible.
Posted Sep 11, 2026 - 14:21 UTC

Investigating

We are investigating elevated errors on requests to Claude Fable 5.1 and Claude Mythos 5.1. We will provide an update as soon as possible.
Posted Sep 11, 2026 - 14:19 UTC
This incident affected: claude.ai, Claude API (api.anthropic.com), Claude Code, and Claude Cowork.