Anthropic outage: Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1

Affected components

• Claude API (api.anthropic.com)
• Claude Code
• Claude Cowork
• claude.ai

1. resolvedOct 5, 2026, 13:21 UTC

   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.

2. investigatingOct 5, 2026, 13:05 UTC

   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.

What APIStatus.watch saw

• Oct 5, 2026, 13:09 UTCoperational → degraded
• Oct 5, 2026, 13:23 UTCdegraded → operational

Other services with incidents at the same time

Overlapping incidents aren't necessarily related.

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• Snyk: Issues API V3 Service - DegradedMinor · Oct 3, 2026, 19:49 UTC
• OpenAI: Elevated Work Mode errorsMinor · Oct 5, 2026, 07:03 UTC
• Twilio: SMS Delivery Delays and Failures Between Twilio Long Codes and Multiple Networks in FranceMinor · Oct 5, 2026, 09:43 UTC
• Twilio: Voice Call Failures from Network Subscribers to a Subset of Twilio France Phone NumbersMinor · Oct 5, 2026, 10:33 UTC

How often does Anthropic have incidents?

Anthropic reported 82 incidents in the last 90 days, 32 of them major or critical. A typical incident lasted 1h 6m. See Anthropic's uptime and incident history