Anthropic incident

Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1

Major Resolved View vendor source →

Anthropic experienced a major incident on September 11, 2026 affecting claude.ai and Claude API (api.anthropic.com) and 1 more component, lasting 17m. The incident has been resolved; the full update timeline is below.

Started
Sep 11, 2026, 02:19 PM UTC
Resolved
Sep 11, 2026, 02:37 PM UTC
Duration
17m
Detected by Pingoru
Sep 11, 2026, 02:19 PM UTC

Affected components

claude.aiClaude API (api.anthropic.com)Claude CodeClaude Cowork

Update timeline

  1. investigating Sep 11, 2026, 02:19 PM UTC

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

  2. identified Sep 11, 2026, 02:21 PM UTC

    We have identified the cause of elevated errors on requests to Claude Mythos 5.1 and Claude Fable 5.1 and are working on a fix. We will provide an update as soon as possible.

  3. monitoring Sep 11, 2026, 02:28 PM UTC

    A fix has been deployed for Claude Mythos 5.1 and Claude Fable 5.1 and we are monitoring for recovery.

  4. monitoring Sep 11, 2026, 02:28 PM UTC

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

  5. resolved Sep 11, 2026, 02:37 PM UTC

    The issue affecting Claude services has been resolved. Impact occurred from 13:57 to 14:20 UTC