Elevated errors for multiple models

Official updates

1. resolved2026-09-03 16:23:12 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.

2. monitoring2026-09-03 16:06:42 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.

3. identified2026-09-03 15:25:20 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.

4. identified2026-09-03 14:49:48 UTC

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

5. identified2026-09-03 13:50:26 UTC

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

6. identified2026-09-03 13:41:19 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.

7. investigating2026-09-03 13:26:04 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.