api - Right HTTP status code to wrong input

Question

What is optimal HTTP response Code when not reporting 200 (everything OK) but error in input?

Like, you submit some data to server, and it will response that your data is wrong

using 500 looks more like Server Issue
using 200 with warning/error response text is bad (allowing caching and everything is not OK)
using 204 and returning nothing, is maybe good (but well supported?)
using 404 is wrong if requested path (script) is available and in proper place

Answer 1

We had the same problem when making our API as well. We were looking for an HTTP status code equivalent to an InvalidArgumentException. After reading the source article below, we ended up using 422 Unprocessable Entity which states:

The 422 (Unprocessable Entity) status code means the server understands the content type of the request entity (hence a 415 (Unsupported Media Type) status code is inappropriate), and the syntax of the request entity is correct (thus a 400 (Bad Request) status code is inappropriate) but was unable to process the contained instructions. For example, this error condition may occur if an XML request body contains well-formed (i.e., syntactically correct), but semantically erroneous, XML instructions.

source: https://www.bennadel.com/blog/2434-http-status-codes-for-invalid-data-400-vs-422.htm