Claude Sonnet 4 degraded performance quality
Jul 10, 02:00 UTC
Resolved - From 08:45 UTC on July 8th to 02:00 UTC on July 10th, Claude Sonnet 4 experienced a degradation in quality for some requests. Users, especially tool use and Claude Code users, would have seen lower intelligence responses and malformed tool calls.
This was caused by a rollout of our inference stack, which we have since rolled back. While we often make changes intended to improve the efficiency and throughput of our models, our intention is always to retain the same model response quality.
via Anthropic Status - Incident History
Jul 10, 02:00 UTC
Resolved - From 08:45 UTC on July 8th to 02:00 UTC on July 10th, Claude Sonnet 4 experienced a degradation in quality for some requests. Users, especially tool use and Claude Code users, would have seen lower intelligence responses and malformed tool calls.
This was caused by a rollout of our inference stack, which we have since rolled back. While we often make changes intended to improve the efficiency and throughput of our models, our intention is always to retain the same model response quality.
via Anthropic Status - Incident History
