Anthropic Claude suffers widespread outage across all models on Aug 18
All Claude models reported elevated errors simultaneously on the morning of Aug 18, with more than 4,000 reports logged within an hour.
On the morning of August 18, 2026, Anthropic Claude suffered a widespread outage across its entire model lineup. Anthropic's status page at status.claude.com flagged elevated errors hitting Claude Mythos 5, Fable 5, Opus 5, Sonnet 5, and Haiku 4.5 all at once, an unusually broad failure that spanned the entire model fleet rather than a single endpoint.
By 9:46 a.m. PT, Downdetector had logged more than 2,000 user reports. Twenty-two minutes later, that number had doubled to more than 4,000. Downdetector's breakdown of reports centered 60 percent on Claude Chat, 24 percent on the mobile app, and 8 percent on Claude Code. The Claude Code share is significant because outages there stall pull requests, break CI pipelines, and stall engineering workflows during the workday.
Anthropic's status page offered little beyond "We are investigating elevated errors on requests to Claude." The failure follows seven separate incidents between August 12 and August 16. As of the same week, claude.ai sat at 99.35 percent uptime, the Claude API at 99.46 percent, Claude Code at 99.38 percent, and Claude Cowork at 99.47 percent, all logged as "degraded performance" rather than fully operational.