# `400` - Invalid request ## Description The request contains some data that is not in the format we expect. ## How to fix - Check the `details` value in the response to get additional information. - Check the expected format for the API call request in the [API Reference](/api). - Check the implementation on your side and make sure that the format of the request matches the expected format for the API endpoint. ## Example ```http HTTP/1.1 400 Bad Request content-length: 228 content-type: application/problem+json date: Mon, 11 Oct 2021 10:42:01 GMT upvest-request-id: e7378103-7d45-4052-a049-7c9ac88d041c { "type": "https://docs.upvest.co/errors/invalid_request", "status": 400, "title": "Invalid request", "request_id": "e7378103-7d45-4052-a049-7c9ac88d041c", "details": "(root): field 'first_name' was not filled" } ```