- Sources: primary, discussion
- Summary: Impact ran from 2026-09-22 00:50 UTC to 02:10 UTC and the incident was marked resolved at 02:35 UTC. Affected surfaces were claude.ai, the Claude API at api.anthropic.com, Claude Code, and Claude Cowork, with elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5. Fable and Mythos recovered first, Opus 5 errors persisted into the final update, and no root cause was published.
- Why it matters: The incident took out a coding agent's backend rather than a consumer chat surface, which is the failure mode teams running agents in CI now have to plan around.
- Follow-up: Whether Anthropic publishes a root cause for the 2026-09-22 incident.
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