Structured outputs unsupported for Azure providers

Applies to:

Plan -
Deployment -

Summary

You see: “structured_outputs not supported in your workspace” when using structured output. Likely cause: the model endpoint or custom provider (for example Azure Foundry) does not support the structured_outputs feature.

Fix: use text output or switch to a provider/model endpoint that supports structured outputs, or update provider configuration if supported.

What is happening

The error is returned by the model provider or model endpoint, not the Braintrust workspace. Some custom provider deployments (notably Azure/custom provider setups) or certain model endpoints do not implement the structured_outputs API feature. When the playground or API request requests structured output, the provider returns an invalid_request_error with that message.

Example minimal error payload:

{
  "error": {
    "message": "structured_outputs not supported in your workspace",
    "type": "invalid_request_error",
    "request_id": "req_0000000000000000000000"
  }
}

This happens when:

A model is routed through a custom provider (Azure Foundry, custom proxy, etc.). AND

The provider/model does not advertise or implement structured output behavior.

Fix or suggestion

Option 1: Use text output (quick workaround)

Switch the prompt/template output mode from Structured to Text in the playground or API request.

Verify the model responds without the structured_outputs error.

Use downstream parsing on the text output if needed.

Option 2: Change provider or model endpoint (preferred for structured data)

Confirm whether the provider or model supports structured_outputs in its documentation or provider feature flags.

If available, point the request to a provider or built-in Braintrust model that supports structured outputs.

Reconfigure your custom provider to a model endpoint/version that advertises structured output support (if the provider offers that capability).

​Summary

​What is happening

​Fix or suggestion

​Option 1: Use text output (quick workaround)

​Option 2: Change provider or model endpoint (preferred for structured data)

Summary

What is happening

Fix or suggestion

Option 1: Use text output (quick workaround)

Option 2: Change provider or model endpoint (preferred for structured data)