Resolved after 2 hours 57 minutes, affecting claude.ai and Claude API (api.anthropic.com) and 1 more, on September 3, 2026.
The issue affecting Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 has been resolved. Impact has ended as of 9:16 PT / 16:16 UTC.
Affected components
Update timeline
- investigating Sep 03, 2026, 01:26 PM UTC
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.
- identified Sep 03, 2026, 01:41 PM UTC
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.
- identified Sep 03, 2026, 01:50 PM UTC
An exhaustive list of affected models: Mythos/Fable 5.1, Mythos/Fable 5, Opus 5, Opus 4.8, Opus 4.6.
- identified Sep 03, 2026, 02:49 PM UTC
We are continuing to work on a fix for this issue.
- identified Sep 03, 2026, 03:25 PM UTC
The only affected models right now are Opus 4.8 and Opus 5. The rest of the models have recovered to baseline error rate.
- monitoring Sep 03, 2026, 04:06 PM UTC
A fix has been deployed for Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 and we are monitoring for recovery.
- resolved Sep 03, 2026, 04:23 PM UTC
The issue affecting Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 has been resolved. Impact has ended as of 9:16 PT / 16:16 UTC.
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