400 vs 422 response to POST that references an unknown entity

Question

I\'m trying to figure out what the correct status code to return on different scenarios with a \"rest-like\" API that I\'m working on.

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Answer 1

I'd say 422 is adequate in your case, but 400 isn't bad if it's consistent with the rest of your API. It's a common convention to use 400 as an umbrella error code when there's something wrong on the client side, but either the error doesn't fit a particular error code, or you don't want to use too many of them.

A 404 is definitely wrong if there's something wrong with the POST payload.