When should HTTP 400 be returned?

The 400 (Bad Request) status code indicates that the server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing). A business rule doesn’t fall under any of those three examples.

For More Information Please Refer: https://softwareengineering.stackexchange.com/questions/329229/should-i-return-an-http-400-bad-request-status-if-a-parameter-is-syntactically