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Anthropic · AIApr 23, 2026, 02:00 UTC

Issues with responses using structured outputs on the API

InformationalNot disclosedUpdated 20h ago
Apr 23, 02:00 UTCApr 23, 02:00 UTC
Duration
0m
Impact
Informational
Root cause
Not disclosed
Anthropic, 90 days
94 incidents
Affected
Not listed by the vendor.
Status page

Final update

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.

Timeline

  1. Resolved · Apr 23, 02:00 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.

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Full history

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