Should a RESTful API return 400 or 404 when passed an invalid id

Question

When building a RESTful API and a user provides an id of resource that does not exist, should you return 404 Not Found or 400 Bad Request

Answer 1

404 would be a more common practice one. Its for Resource Not Found. In your case the particular URL is not found.

400 is generally used for Bad Request. You can use this one for any bad request. For eg. MissingRequiredQueryParameter, InvalidInput.