Incident archive

Claude outage September 15, 2026

Intermittent error spikes for Claude Mythos 5.1 and Claude Fable 5.1

Claude claude.ai was down for 1 h 26 min on September 15, 2026.

Claude recorded a major-impact incident affecting claude.ai, Claude API (api.anthropic.com), Claude Code, Claude Cowork on September 15, 2026. It ran for 1 h 26 min — 19 min longer than the archive median of 1 h 7 min.

Started
September 15, 2026, 09:48 UTC
Resolved
September 15, 2026, 11:14 UTC
Duration
1 h 26 min
Impact
Major

What was affected?

How long did it last?

  1. September 15, 2026, 09:48 UTCinvestigatingT+0
  2. September 15, 2026, 09:52 UTCinvestigatingT+4 min
  3. September 15, 2026, 10:50 UTCmonitoringT+1 h 2 min
  4. September 15, 2026, 11:14 UTCresolvedT+1 h 26 min

Has this happened before?

This was incident 10 of 10 recorded in September 2026, totalling 109 h 47 min of reported disruption across all Claude components that month. claude.ai was affected by 18 other recorded incidents in the 30 days before this one started. The previous incident touching claude.ai started on September 11, 2026. These comparisons are drawn from our archive, which starts on July 14, 2026. See the full outage history.

Summarized by Claude Network from Claude Status. Last verified .