A two-phase incident affected models: between 17:23 and 18:00 UTC all Sonnet and Opus models reached around a 10 percent error rate, and from 18:00 to 19:20 UTC Opus 4.8 averaged a 10 percent error rate. Full resolution came by 19:32 UTC on June 16.
Elevated errors across many models
calendar_today
June 16, 2026
domain
claude