# invalid_request

> Noptcha API error invalid_request (HTTP 400): what it means and what to do.

Source: https://noptcha.com/docs/errors/invalid_request/

HTTP **400**, `application/problem+json`. When: malformed body, missing field, bad parameter, `callback_url` not a string.

## What to do

The request itself is malformed: the body is not a JSON object, a field is missing or has the wrong type, a header such as `Idempotency-Key` is invalid, or `callback_url` is not a string. `detail` says what is wrong. Fix the request; retrying it unchanged gives the same error.

See all codes on [Errors](https://noptcha.com/docs/errors.md). Include the `request_id` when you contact support.