Anthropic Investigating Elevated Errors Across Multiple Claude Models

Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 experiencing service disruptions.

By The Downtime · Sep 22, 2026 · 1:02 AM ·Updated 1 hour ago

Anthropic is investigating elevated errors affecting requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5. The company has classified the incident as major and is currently working to identify the root cause.

Anthropicis an AI safety company that develops Claude, a large language model used by developers, enterprises, and researchers for various applications including content generation, analysis, and automation tasks.

The company reported the issue on its status page but has not yet provided specifics on error rates, affected regions, or duration. An update is expected as the investigation progresses.

This is a developing story. The Downtime will continue monitoring and update as new information becomes available.

🕒 Live updates (5)

resolved Sep 22, 2:35 AM

This issue has been resolved. Impact occurred from 5:50pm PT / 00:50 UTC to 7:10pm PT / 02:10 UTC.

monitoring Sep 22, 2:11 AM

We have seen success rates return to normal across affected models, and are monitoring closely to ensure no further issues.

identified Sep 22, 1:35 AM

We are continuing to work to resolve errors affecting some models. At this time, requests to Claude Fable 5 and 5.1 and Mythos 5 and 5.1 have returned to normal success rates. We are working to resolve remaining errors affecting Claude Opus 5, and will provide an additional update shortly.

identified Sep 22, 1:17 AM

We have identified the cause of elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 and are working on a fix. We will provide an update as soon as possible.

investigating Sep 22, 12:57 AM

We are investigating elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5. We will provide an update as soon as possible.

📎 Sources

Anthropic status ↗

Outage details are aggregated from official provider status pages. The Downtime reports them as a public service and is not affiliated with the providers named.