400 Error When Using proxyOrdering

Last updated: March 13, 2026

This issue is applicable to customers matching these conditions

Plans: Any

Deployments: Any

Use case: Structured output with Gemini models

Issue

While using the proxyOrdering field in structured output on Gemini models, you notice the below error message:

error:
  code: 400
  details:
    - '@type': type.googleapis.com/google.rpc.BadRequest
      fieldViolations:
        - description: 'Invalid JSON payload received. Unknown name "x-propertyOrdering" at ''generation_config.response_schema'': Cannot find field.'
          field: generation_config.response_schema
  message: 'Invalid JSON payload received. Unknown name "x-propertyOrdering" at ''generation_config.response_schema'': Cannot find field.'
  status: INVALID_ARGUMENT

Cause

This is an issue with the proxy converting the propertyOrdering field in structured output to x-property-ordering.

Resolution(s)

If you do not need this field in your payload:

Step 1: Click the Output dropdown on your Prompt.

Step 2: Choose Structured Output.

Step 3: Remove proxyOrdering from the object builder.

Otherwise:

Contact support and ask if it is possible to enable the API Gateway in your Control Plane.