Cloud-based AI models provided by OpenAI, Anthropic, xAI, and Google experienced a rare set of simultaneous and significant service outages on Thursday morning.
Anthropic first reported a “partial outage” in Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 at 9:23 a.m. Eastern Time; the cause of the incident was identified and resolved approximately 15 minutes later, and the service returned to normal operation by 12:16 p.m. On the same day, a separate report indicated that Claude Sonnet 5 requests also briefly experienced increased error rates after noon.
Meanwhile, OpenAI announced that increased error rates in ChatGPT and Codex had been causing a “service degradation” since 10:43 a.m. A workaround implemented about half an hour later resolved the issue by 12:55 p.m.