Mythos, Fable, Opus 5 hitting errors simultaneously. Prod-dependent builders should verify fallbacks now.
Elevated errors on multiple Claude models under investigation
Original: Elevated errors for multiple models
Importance: 本番環境で複数モデルに同時発生する障害は即影響を及ぼす可能性が高い
Summary
Anthropic is investigating elevated error rates affecting requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 as of September 3, 2026. The root cause and recovery timeline have not yet been disclosed. Users relying on these models via API or Claude.ai should expect potential service disruption.
Key Points
- Error rates elevated on Mythos 5.1, Fable 5.1, Opus 5
- Root cause and ETA not disclosed; investigation ongoing
- Both API and Claude.ai users potentially affected
- Latest updates available at status.claude.com
View developer notes (APIs, breaking changes, migration)
Error rates elevated for Claude Mythos 5.1, Fable 5.1, and Opus 5 models. Incident tracked at status.claude.com (ID: 461yvfrzpwtt). Developers using these models in production should immediately enhance monitoring and verify fallback strategies. No ETA or RCA published yet.
Source: https://status.claude.com/incidents/461yvfrzpwtt
Outlet: Anthropic Status
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