Discussion Hub for new Claude incident: Elevated errors for multiple models on Sep 3, 2026
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Claude model activity is surfacing — worth tracking for capability changes, ecosystem impact, and availability.
On September 3, 2026, Claude experienced elevated errors across multiple models, including Mythos 5.1, Fable 5.1, Opus 5, Opus 4.8, and Opus 4.6. The issue was first identified and investigated, with a fix subsequently deployed. By 15:25 UTC, most models had recovered, leaving only Opus 4.8 and Opus 5 affected. The problem was fully resolved by 16:16 UTC, with monitoring confirming recovery for all impacted models.
Resolved - 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. Sep 3, 16:23 UTC
Monitoring - A fix has been deployed for Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 and we are monitoring for recovery. Sep 3, 16:06 UTC
Update - The only affected models right now are Opus 4.8 and Opus 5. The rest of the models have recovered to baseline error rate. Sep 3, 15:25 UTC
Update - We are continuing to work on a fix for this issue. Sep 3, 14:49 UTC
Update - An exhaustive list of affected models: Mythos/Fable 5.1, Mythos/Fable 5, Opus 5, Opus 4.8, Opus 4.6. Sep 3, 13:50 UTC
Identified - 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. Sep 3, 13:41 UTC
Investigating - 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. Sep 3, 13:26 UTC
Post flair and post body will be updated as the incident report is updated by Anthropic.
This discussion post will be removed from subreddit highlights one hour after the incident is resolved.
View this incident on status.claude.com