Mythos/Fable/Opus 5 down, root cause identified but ETA unclear. Production ops teams: heighten monitoring now.
Elevated error rates on Claude Mythos 5, Fable 5, and Opus 5 — cause identified
Original: Degraded performance for Claude Mythos 5, Claude Fable 5, and Claude Opus 5
Importance: 本番稼働中のClaudeベースサービスに即座の影響が出ており、エラー率上昇は可用性を直撃している
Summary
Anthropic's status page reports elevated error rates affecting requests to Claude Mythos 5, Claude Fable 5, and Claude Opus 5. Anthropic has identified the root cause and is working on a fix, with updates to follow. Developers and SaaS operators relying on these models in production should heighten API response monitoring and prepare fallback mechanisms. Full resolution details and ETA remain pending.
Key Points
- Error rate increase on Mythos/Fable/Opus 5
- Anthropic has identified root cause
- Recovery ETA not yet disclosed
- Production impact possible
View developer notes (APIs, breaking changes, migration)
API endpoints for Claude Mythos 5, Claude Fable 5, and Opus 5 are experiencing elevated error rates. Anthropic has identified the root cause but has not disclosed technical details such as error codes, affected endpoints, or impact on context window or inference latency. Developers using the messages API should implement retry logic (exponential backoff recommended), deploy circuit breaker patterns, and evaluate routing to fallback models. The lack of ETA requires immediate SLA risk assessment.
Source: https://status.claude.com/incidents/f6gkkq6txl7z
Outlet: Anthropic Status
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