Anthropic incident

Issues with responses using structured outputs on the API

Notice Resolved View vendor source →

Anthropic experienced a notice incident on April 23, 2026, lasting —. The incident has been resolved; the full update timeline is below.

Started
Apr 23, 2026, 09:25 PM UTC
Resolved
Apr 23, 2026, 02:00 AM UTC
Duration
—
Detected by Pingoru
Apr 23, 2026, 09:25 PM UTC

Update timeline

  1. resolved Apr 23, 2026, 09:25 PM UTC

    We have identified and resolved an issue which resulted in issues with model responses when making use of structured outputs via the Anthropic API between 16:10 UTC on April 22 and 01:59 UTC on April 23. During this period, structured outputs containing some forms of grammar requirements returned with reduced quality. This did not impact any requests not using structured outputs, as detailed here: https://platform.claude.com/docs/en/build-with-claude/structured-outputs.