Incident report · read from Anthropic's status page

Anthropic incident: Elevated errors for Claude Mythos 5, Claude Fable 5, and Claude Sonnet 5

Resolved after 1 h 34 m (13 Aug 2026, 14:33–16:08 UTC), impact major, affecting Claude Cowork, Claude API (api.anthropic.com), claude.ai and Claude Code.

Timeline

1. 13 Aug 2026 at 14:33 UTC investigating

   We are investigating elevated errors on requests to Claude Mythos 5, Claude Fable 5, and Claude Sonnet 5. We will provide an update as soon as possible.

2. 13 Aug 2026 at 15:44 UTC investigating

   We are investigating elevated errors on requests to Claude Mythos 5 and Claude Fable 5. We will provide an update as soon as possible.

3. 13 Aug 2026 at 16:08 UTC resolved

   The issue affecting Claude Mythos 5 and Claude Fable 5 has been resolved.

Affected components

• Claude Cowork: partial outage for 1 h 34 m
• Claude API (api.anthropic.com): partial outage for 1 h 34 m
• claude.ai: partial outage for 1 h 34 m
• Claude Code: partial outage for 1 h 34 m

Source

Anthropic's own report of this incident, on Anthropic's status page. This page is a record of Anthropic's own report; where the two disagree, theirs is right.

Last checked 8 Sep 2026 at 16:18 UTC.

Must Have AI is a parody and is not affiliated with, endorsed by or connected to OpenAI, Anthropic or Google. Every outage shown here is read from the provider's own public status page.