Changes / Claude / Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1
Claude: Major incident: Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1
Summary
Claude reported major 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. The incident started at 2026-10-05 13:05 UTC and resolved at 2026-10-05 13:21 UTC (computed duration: 15 min); the vendor separately stated an impact window of 12:40 UTC to 13:10 UTC.
Machine-written from the diff below (Sol; type: incident outage). Check the diff before relying on it.
What changed
Before: not present
After: Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1
Before: not present
After: major
Before: not present
After: resolved
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After: 2026-10-05 13:05 UTC
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After: 2026-10-05 13:21 UTC
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After: claude.ai, Claude API (api.anthropic.com), Claude Code, Claude Cowork
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After: 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.
Before: not present
After: 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.
First version of this incident archived by Rewindex. View the live incident.
History of this incident
| When (UTC) | Change | Kind |
|---|---|---|
| Major incident: Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1 (this change) Claude reported major 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. The incident started at 2026-10-05 13:05 UTC and resolved at 2026-10-05 13:21 UTC (computed duration: 15 min); the vendor separately stated an impact window of 12:40 UTC to 13:10 UTC. | Major incident |