Anthropic outage: Elevated errors for Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5

Affected components

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

1. resolvedOct 24, 2026, 00:11 UTC

   The issue affecting Claude models has been resolved. Impact occurred from 16:28 PT / 23:28 UTC on October 23 to 16:59 PT / 23:59 UTC on October 23.

2. monitoringOct 23, 2026, 23:54 UTC

   We are seeing success rates return to normal for all affected models, and are continuing to monitor to ensure no further issues.

3. identifiedOct 23, 2026, 23:39 UTC

   We have identified the cause of elevated errors on requests to Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5, as well as fast mode requests to Opus 5.5 and are working on a fix. We will provide an update as soon as possible.

4. investigatingOct 23, 2026, 23:37 UTC

   We are investigating elevated errors on requests to Claude Fable 5.1. We will provide an update as soon as possible.

What APIStatus.watch saw

• Oct 23, 2026, 23:38 UTCoperational → partial outage
• Oct 23, 2026, 23:58 UTCpartial outage → degraded
• Oct 24, 2026, 00:13 UTCdegraded → operational
• Oct 24, 2026, 00:33 UTCoperational → degraded
• Oct 24, 2026, 00:38 UTCdegraded → operational

Other services with incidents at the same time

Overlapping incidents aren't necessarily related.

• Snyk: Snyk Container Degradation in SNYK-US-01Major · Oct 22, 2026, 21:53 UTC
• Snyk: Snyk Test Down in SNYK-US-01Major · Oct 23, 2026, 14:10 UTC
• Cursor: Investigating service outage - Grok models unavailableMajor · Oct 23, 2026, 23:39 UTC
• Twilio: Voice Call Post Dial Delay from a Subset of Twilio Phone Numbers to ThailandMinor · Oct 12, 2026, 11:53 UTC
• Twilio: SMS Delivery Delays and Failures from Twilio Short Codes to Multiple Networks in IndiaMinor · Oct 21, 2026, 16:32 UTC
• Supabase: Elevated Mgmt API Error Rates in Multiple RegionsMinor · Oct 22, 2026, 17:01 UTC
• Twilio: Voice Call Post Dial Delay from Twilio Phone Numbers to ChileMinor · Oct 23, 2026, 14:53 UTC
• Twilio: SMS Delivery Delays from a Subset of Twilio Phone Numbers to Telefonica NicaraguaMinor · Oct 23, 2026, 16:19 UTC
• Twilio: SMS Delivery Failures from Twilio to South AfricaMinor · Oct 23, 2026, 19:46 UTC
• Twilio: SMS Delivery Delays From a Subset of Twilio Alphanumeric Sender IDs, Short Codes, and Long Codes to Claro BrazilMinor · Oct 23, 2026, 20:06 UTC

How often does Anthropic have incidents?

Anthropic reported 53 incidents in the last 90 days, 25 of them major or critical. A typical incident lasted 1h 3m. See Anthropic's uptime and incident history