AI BriefingIncident and Recovery for Multiple Claude Models
Key point
The performance degradation incident affecting multiple models, including Claude Opus 5, on August 18 was resolved in approximately two hours.
Details
From 16:11 UTC to 18:23 UTC on August 18, 2026, an incident involving performance degradation and errors occurred across multiple Claude models, including Claude Opus 5.
Anthropic began investigating the incident at 16:20 UTC and confirmed that various models were affected, including Claude Mythos 5, Claude Fable 5, Claude Sonnet 5, and Claude Haiku 4.5.
A fix was applied at 18:26 UTC with monitoring initiated, and the official announcement of full resolution was made at 19:01 UTC.
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