What is the most appropriate HTTP status code to return if a required header is missing?
问题 I read What HTTP status response code should I use if the request is missing a required parameter? but it did not specifically ask about headers and there didn't seem to be a consensus. The context of this question assumes successful authentication. I'm currently favoring either a 400 (though that doesn't feel right because this isn't really a case of "malformed syntax") or 403. Given 403's description: The server understood the request, but is refusing to fulfill it. Authorization will not