> ## Documentation Index
> Fetch the complete documentation index at: https://wb-21fd5541-docs-sandboxes-integrations-placement.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# API error code 422 - Invalid request parameters

Invalid parameters on chat completion requests often surface as **HTTP 422 (Unprocessable Entity)** or **HTTP 400 (Bad Request)** depending on where validation runs. In both cases, read the response body before changing your request.

## 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 can return **400** or **422**.
* **Parameter value out of range**: Values like `temperature` must fall within a valid range for the model (often **0–2**). Out-of-range values are often rejected with **HTTP 400** and an `error.message` that names the parameter.
* **Malformed `messages` payload**: The `messages` field must be a list of message objects. Wrong types or invalid structure typically return **HTTP 400** with a validation message in the response body.
* **Invalid `response_format` or other structured-output settings**: Requesting a format the model does not support can return an error response. Treat the status code and body as authoritative for your model.

## What you can do

1. **Check the error message body**
   * Many responses use an `error` object with a `message` field (and sometimes `param` or `code`). Some layers return a `detail` field instead. Read whichever field the response includes before troubleshooting.

2. **Verify parameter support for your model**
   * Review [Available models](/inference/models) 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 [chat completions API reference](/inference/api-reference/chat-completions) for the correct schema.

4. **Confirm the base URL**
   * Point your OpenAI-compatible client at `https://api.inference.wandb.ai/v1`, not `https://api.wandb.ai`. The Multi-tenant Cloud API host does not serve Inference chat completions. For optional usage attribution, set the `OpenAI-Project` header to `team/project` as in the [list models API reference](/inference/api-reference/list-models).

5. **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 can trigger **400** or **422** responses.

For more information, see [Serverless Inference](/inference) and the [chat completions API reference](/inference/api-reference/chat-completions).

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