A 422 status code occurs when a request is well-formed, however, due to semantic errors it is unable to be processed. This HTTP status was introduced in RFC 4918 and is more specifically geared toward HTTP extensions for Web Distributed Authoring and Versioning (WebDAV).

What is a status code 422?

The HyperText Transfer Protocol (HTTP) 422 Unprocessable Entity response status code indicates that the server understands the content type of the request entity, and the syntax of the request entity is correct, but it was unable to process the contained instructions.

What is the status code 400?

The HyperText Transfer Protocol (HTTP) 400 Bad Request response status code indicates that the server cannot or will not process the request due to something that is perceived to be a client error (for example, malformed request syntax, invalid request message framing, or deceptive request routing).