Update
We are continuing to activity to determine errors affecting several models. At this time, requests to Claude Fable 5 and 5.1 and Mythos 5 and 5.1 have returned to normal achievement rates. We are operating to determine remaining errors affecting Claude Opus 5, and volition provision an additional update shortly.
Posted Sep 22, 2026 - 01:35 UTC
Identified
We have identified the logic of elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 and are operating on a fix. We volition provision an update as shortly as possible.
Posted Sep 22, 2026 - 01:17 UTC
Investigating
We are examining elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5. We volition provision an update as shortly as possible.
Posted Sep 22, 2026 - 00:57 UTC
This event affects: claude.ai, Claude API (api.anthropic.com), Claude Code, and Claude Cowork.
