Elevated errors for Claude Fable 5.1

Anthropic reported elevated errors on requests to Claude Fable 5.1, Sonnet 5.5 and Haiku 5.5, plus fast mode requests to Opus 5.5, saying it had identified the cause and was working on a fix as of Oct 23, 2026 at 23:39 UTC. The incident, first flagged as under investigation at 23:37 UTC, affects claude.ai, the Claude API at api.anthropic.com, Claude Code and Claude Cowork. Anthropic did not state how many requests were failing or when service would be restored.

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. Posted Oct 23, 2026 - 23:39 UTC Investigating We are investigating elevated errors on requests to Claude Fable 5.1. We will provide an update as soon as possible. Posted Oct 23, 2026 - 23:37 UTC This incident affects: claude.ai, Claude API api.anthropic.com , Claude Code, and Claude Cowork. Subscribe to updates for Elevated errors for Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5 via email and/or text message. You'll receive email notifications when incidents are updated, and text message notifications whenever Claude creates or resolves an incident.