Outage in Anthropic
Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1
Resolved MajorIncident Report
Summary AI Generated
On September 11, 2026, Claude Mythos 5.1 and Claude Fable 5.1 experienced elevated error rates affecting both api.anthropic.com and claude.ai for approximately 19 minutes (13:57–14:20 UTC). The root cause was identified and a fix was deployed, after which services were monitored and confirmed fully resolved.
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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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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