Claude Reports Elevated Errors for Sonnet 5.5 and Other Models

2:14 a.m. Eastern on October 25, 2026, marked Investigating

We are investigating elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5. We will provide an update as soon as possible.

2:27 a.m. Eastern on October 25, 2026, marked Identified

We have identified the cause of elevated errors on requests to Claude Sonnet 5.5 and are working on a fix. We will provide an update as soon as possible.

2:35 a.m. Eastern on October 25, 2026, marked Monitoring

A fix has been deployed for the issue affecting Claude services and we are monitoring for recovery.