Anthropic opened an investigation at 06:14 UTC on October 25 into elevated errors on requests to five models: Claude Mythos 5.1, Claude Fable 5.1, Claude Opus 5.5, Claude Sonnet 5.5 and Claude Haiku 5.5. The status page marked claude.ai, the Claude API, Claude Code and Claude Cowork as partial outage, while Claude Console and Claude for Government remained operational.

The timeline was short. Anthropic identified the cause at 06:27 UTC, focusing on Sonnet 5.5, deployed a fix and moved to monitoring at 06:35 UTC, and marked the incident resolved at 07:53 UTC, with the actual impact window stated as 06:05 to 06:35 UTC (11:05 to 11:35 PM PT on October 24). A second, smaller incident followed the same morning, with elevated errors on Fable 5.1 from 08:08 to 08:29 UTC.

The incidents follow three resolved error incidents on October 24 and another on October 22, according to incident tracking of the Claude status page. For users of the flagship apps, the practical story is a short overnight disruption rather than a prolonged outage, in a month that has already seen a broader Claude outage on September 29.