API error code 422 - Invalid request parameters

A 422 error means the request was understood by the server but could not be processed because one or more parameters are invalid, missing, or out of range.

Why this happens

• Unsupported parameter for the model: Some parameters (such as frequency_penalty, logprobs, or response_format) are not supported by all models. Passing an unsupported parameter returns a 422.
• Parameter value out of range: Values like temperature must fall within a valid range (typically 0–2). Passing a value outside that range causes a 422.
• Malformed messages array: The messages field must be a list of objects with role and content keys. Missing or incorrectly typed fields return a 422.
• Invalid response_format: Requesting JSON mode (response_format: {"type": "json_object"}) with a model that does not support structured outputs causes a 422.

What you can do

1. Check the error message body

   • The 422 response body contains a detail field that identifies which parameter is invalid and why. Read it before troubleshooting.

2. Verify parameter support for your model

   • Review the W&B Inference supported models list for the specific parameters and ranges each model accepts.

3. Validate your messages array

   • Each message must have a role (system, user, or assistant) and a content string. Tool call messages require additional fields—consult the API reference for the correct schema.

4. Remove unsupported parameters

   • If you are adapting code from another provider, remove any parameters that are not in the W&B Inference API reference. Extra parameters that the model does not support will trigger a 422.

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