Anthropic change history

Anthropic reported a major incident affecting usage data on platform.claude.com Usage and Rate limits pages and the Admin API usage report, starting 2026-10-07 13:25 UTC and resolved 2026-10-13 18:00 UTC (6 days 4 h). Mitigations reduced errors, but recent usage could remain delayed while a full fix was pending; core functionality and API requests were unaffected.

Anthropic reported major errors loading platform.claude.com Usage page and Admin API usage reports; Messages API requests were unaffected. Tracked from 2026-10-07 01:20 UTC until resolution at 2026-10-07 02:33 UTC (1 h 13 min), the incident’s resolution update specified errors from 00:00 UTC on October 7 to 01:40 UTC on October 7.

Claude Opus 5.5 requests experienced elevated errors affecting claude.ai, Claude API (api.anthropic.com), Claude Code, and Claude Cowork. Anthropic rated the impact major; the incident started at 2026-10-06 12:24 UTC and was resolved at 2026-10-06 12:43 UTC, lasting 18 min. Anthropic identified the cause but did not disclose it or the fix.

Anthropic reported a major incident with elevated errors for Claude Mythos 5.1 and Claude Fable 5.1 across claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork. It started 2026-10-05 13:05 UTC and resolved at 2026-10-05 13:21 UTC (computed duration: 15 min); the vendor reported impact from 12:40 UTC to 13:10 UTC.

Anthropic reported major errors affecting claude.ai, Claude Code, Claude Cowork and the Claude API, blocking sign-ins, new sessions, purchases and uploads; some messages may not have been saved. Impact occurred from 14:00 UTC to 14:59 UTC; the incident started 2026-09-29 14:21 UTC and resolved at 2026-09-29 16:27 UTC (recorded duration: 2 h 5 min).

Anthropic reported a major outage with elevated request errors affecting Claude Mythos 5 and 5.1, Claude Fable 5 and 5.1, and Claude Opus 5. The incident started 2026-09-22 00:57 UTC and resolved at 2026-09-22 02:35 UTC (1 h 37 min); Anthropic stated actual impact occurred from 00:50 UTC to 02:10 UTC.

Anthropic reported major intermittent error spikes for Claude Mythos 5.1 and Claude Fable 5.1, affecting claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork. The incident started at 2026-09-15 09:48 UTC and was resolved at 2026-09-15 11:14 UTC, lasting 1 h 26 min; a fix was deployed by 10:50 UTC.

Anthropic reported major elevated errors for Claude Mythos 5.1 and Claude Fable 5.1 across claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork. The incident started 2026-09-11 14:19 UTC, lasted 17 min and was resolved after a fix was deployed; Anthropic separately reported impact from 13:57 to 14:20 UTC.

Claude Cowork on Windows could not run local commands after a September 8 Windows update blocked workspace access to the computer’s drive; chat and file reading/editing still worked for most users. Anthropic rated the incident major, from 2026-09-10 15:54 UTC to 2026-09-14 19:14 UTC (4 days 3 h). Microsoft’s September 14 Windows update fixed it.

Anthropic reported a major incident causing elevated request errors across claude.ai, Claude API (api.anthropic.com), Claude Code, and Claude Cowork, initially affecting Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5. Starting 2026-09-03 13:26 UTC, it was resolved at 2026-09-03 16:23 UTC (2 h 57 min); a fix was deployed.

Claude Sonnet 5 requests experienced elevated errors across claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork, with major impact. The incident started at 2026-09-03 12:37 UTC and was resolved at 2026-09-03 12:56 UTC; the reported duration was 18 min. Anthropic implemented a fix and monitored results before resolution.

Claude Sonnet 5 requests experienced elevated errors affecting claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork. Anthropic rated the incident major; it started at 2026-09-02 21:17 UTC and was resolved after 26 min. The resolution update separately reported customer impact from 21:05 UTC to 21:19 UTC.

Anthropic reported a major outage affecting Claude Cowork and Claude Code on the web: some sessions failed to start or disconnected mid-task due to an upstream cloud provider issue. It started at 2026-08-28 17:22 UTC and was resolved at 2026-08-28 20:21 UTC, lasting 2 h 59 min. A mitigation was applied; affected sessions could be retried.

Anthropic reported a major incident involving elevated errors on claude.ai, Claude API (api.anthropic.com), Claude Code, and Claude Cowork. Started: 2026-08-24 05:06 UTC; resolved: 2026-08-24 08:30 UTC; duration: 3 h 24 min. The final update reported user errors from 04:50 UTC through 07:36 UTC, including requests to Claude Opus 5 and Fable 5.

Anthropic reported a major incident involving elevated errors on requests to some Claude models, affecting claude.ai, Claude API (api.anthropic.com), Claude Code, and Claude Cowork. It started at 2026-08-20 19:16 UTC and was resolved at 2026-08-20 19:42 UTC, lasting 26 min; no cause or specific fix was stated.

Anthropic reported a critical disruption involving authentication issues and degraded performance across claude.ai, Claude API, Claude Code, Claude Console, and Claude Cowork. It started at 2026-08-16 21:58 UTC and was resolved at 2026-08-16 22:34 UTC, lasting 35 min; a fix was deployed at 22:22 UTC.

Claude Fable 5 requests on claude.ai experienced elevated errors, rated major. The incident started at 2026-08-14 23:57 UTC and resolved at 2026-08-15 00:27 UTC (30 min). Anthropic separately reported impact from 20:00 Aug 14, 2026 to 00:11 Aug 15 , 2026 UTC; no specific cause or fix was disclosed.

A major degradation affected Claude API (api.anthropic.com), Claude Code, and Claude Cowork. The incident started at 2026-08-14 20:30 UTC and was resolved at 2026-08-14 21:58 UTC (1 h 27 min); Anthropic reported customer impact from 20:14 to 20:38 UTC. A fix was deployed at 20:44 UTC, but no specific cause was disclosed.

Anthropic reported a major incident with elevated request errors for Claude Mythos 5, Claude Fable 5, and Claude Sonnet 5, affecting claude.ai, Claude API (api.anthropic.com), Claude Code, and Claude Cowork. It started at 2026-08-13 14:33 UTC and was resolved at 2026-08-13 16:08 UTC, lasting 1 h 34 min; no cause or fix was stated.

Anthropic reported a major incident affecting claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork: some users had login issues, including OAuth, and model request errors. It started at 2026-08-04 20:48 UTC and was resolved at 2026-08-04 21:59 UTC, lasting 1 h 11 min; no specific cause or fix was stated.

Anthropic reported a major incident with elevated errors across many models affecting claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork. It started at 2026-07-30 05:57 UTC and was resolved at 2026-07-30 10:48 UTC, lasting 4 h 51 min; models partially recovered before errors returned across all models.

Anthropic reported a critical incident involving elevated errors across all models, affecting claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork. The incident started at 2026-07-29 19:49 UTC and was resolved at 2026-07-29 22:36 UTC, lasting 2 h 46 min; Anthropic reported recovery in success rates across all models.