Anthropic: Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1

Impact: majorStatus: resolvedStarted 2026-10-05 13:05 UTCResolved 2026-10-05 13:21 UTC (16 min)2 updatesSource: stspg.io

Summary

Anthropic reported a major incident with elevated errors for Claude Mythos 5.1 and Claude Fable 5.1 across claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork. It started 2026-10-05 13:05 UTC and resolved at 2026-10-05 13:21 UTC (computed duration: 15 min); the vendor reported impact from 12:40 UTC to 13:10 UTC.

Machine-written from the archived incident (Sol). Check the timeline before relying on it.

Affected components: Claude CoworkClaude API (api.anthropic.com)claude.aiClaude Code

Timeline of updates

investigating2026-10-05 13:05 UTC
We are investigating elevated errors on requests to Claude Mythos 5.1 and Claude Fable 5.1. We will provide an update as soon as possible.
resolved2026-10-05 13:21 UTC
The issue affecting Claude Mythos 5.1 and Claude Fable 5.1 has been resolved. Impact occurred from 05:40 PT / 12:40 UTC to 06:10 PT / 13:10 UTC.

Rewindex changes for this incident

Major incident: Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1 2026-10-05 13:05 UTC

Impact, status and times are the vendor’s own, as last archived. View on stspg.io (opens in new tab). Anthropic profile · Recent Anthropic incidents · Markdown · JSON