Outage in Claude

Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1

Resolved Major

September 11, 2026 - Started 3 days ago - Lasted 16 minutes
Official incident page

Incident Report

Summary AI Generated

Claude Mythos 5.1 and Claude Fable 5.1 experienced elevated error rates for 16 minutes on September 11, 2026 (13:57–14:20 UTC), affecting both api.anthropic.com and claude.ai. The root cause was identified and a fix was deployed. The incident was fully resolved with no further impact.

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.

Components affected

Claude claude.ai Claude api.anthropic.com

Latest Updates ( sorted recent to last )

RESOLVED 3 days ago - at 09/11/2026 02:37PM

The issue affecting Claude services has been resolved. Impact occurred from 13:57 to 14:20 UTC

MONITORING 3 days ago - at 09/11/2026 02:28PM

A fix has been deployed for the issue affecting Claude services and we are monitoring for recovery.

MONITORING 3 days ago - at 09/11/2026 02:28PM

A fix has been deployed for Claude Mythos 5.1 and Claude Fable 5.1 and we are monitoring for recovery.

IDENTIFIED 3 days ago - at 09/11/2026 02:21PM

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.

INVESTIGATING 3 days ago - at 09/11/2026 02:19PM

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.

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