Anthropic incident

Intermittent error spikes for Claude Mythos 5.1 and Claude Fable 5.1

Resolved after 1 hour 26 minutes, affecting claude.ai and Claude API (api.anthropic.com) and 1 more, on September 15, 2026.

resolved Sep 15, 2026, 11:14 AM UTC

A fix has been deployed for Claude Mythos 5.1 and Claude Fable 5.1 and we are monitoring to ensure it has resolved the issue.

Started
Sep 15, 2026, 09:48 AM UTC
Resolved
Sep 15, 2026, 11:14 AM UTC
Duration
1h 26m
Detected by Pingoru
Sep 15, 2026, 09:48 AM UTC

Affected components

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

Update timeline

  1. investigating Sep 15, 2026, 09:48 AM UTC

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

  2. investigating Sep 15, 2026, 09:52 AM UTC

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

  3. monitoring Sep 15, 2026, 10:50 AM UTC

    A fix has been deployed for Claude Mythos 5.1 and Claude Fable 5.1 and we are monitoring to ensure it has resolved the issue.

  4. resolved Sep 15, 2026, 11:14 AM UTC

    A fix has been deployed for Claude Mythos 5.1 and Claude Fable 5.1 and we are monitoring to ensure it has resolved the issue.

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