Changes / Claude / Elevated errors for multiple models
Claude: Major incident: Elevated errors for multiple models
Summary
Claude reported a major incident with elevated errors affecting multiple models across claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork. It started at 2026-09-03 13:26 UTC and was resolved at 2026-09-03 16:23 UTC, lasting 2 h 57 min. A fix was deployed; the vendor said customer impact ended at 16:16 UTC.
Machine-written from the diff below (Sol; type: incident outage). Check the diff before relying on it.
What changed
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After: Elevated errors for multiple models
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After: major
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After: resolved
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After: 2026-09-03 13:26 UTC
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After: 2026-09-03 16:23 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, Claude Fable 5.1, and Claude Opus 5. We will provide an update as soon as possible.
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After: 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.
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After: An exhaustive list of affected models: Mythos/Fable 5.1, Mythos/Fable 5, Opus 5, Opus 4.8, Opus 4.6.
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After: We are continuing to work on a fix for this issue.
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After: The only affected models right now are Opus 4.8 and Opus 5. The rest of the models have recovered to baseline error rate.
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After: A fix has been deployed for Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 and we are monitoring for recovery.
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After: 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.
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History of this incident
| When (UTC) | Change | Kind |
|---|---|---|
| Major incident: Elevated errors for multiple models (this change) Claude reported a major incident with elevated errors affecting multiple models across claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork. It started at 2026-09-03 13:26 UTC and was resolved at 2026-09-03 16:23 UTC, lasting 2 h 57 min. A fix was deployed; the vendor said customer impact ended at 16:16 UTC. | Major incident |