Elevated errors for multiple 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.

9/3/2026, 4:23:12 PM

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.

9/3/2026, 4:06:42 PM

identified

The only affected models right now are Opus 4.8 and Opus 5. The rest of the models have recovered to baseline error rate.

9/3/2026, 3:25:20 PM

identified

We are continuing to work on a fix for this issue.

9/3/2026, 2:49:48 PM

identified

An exhaustive list of affected models: Mythos/Fable 5.1, Mythos/Fable 5, Opus 5, Opus 4.8, Opus 4.6.

9/3/2026, 1:50:26 PM

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.

9/3/2026, 1:41:19 PM

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.

9/3/2026, 1:26:04 PM