Anthropic incident

Intermittent error spikes for Claude Mythos 5.1 and Claude Fable 5.1

Major Resolved View vendor source →

Anthropic experienced a major incident on September 15, 2026 affecting claude.ai and Claude API (api.anthropic.com) and 1 more component, lasting 1h 26m. The incident has been resolved; the full update timeline is below.

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.