200 OK: Success!
304 Not Modified: There was no new data to return.
400 Bad Request: The request was invalid. An accompanying error message will explain why. This is the status code will be returned during rate limiting.
401 Unauthorized: Authentication credentials were missing or incorrect.
403 Forbidden: The request is understood, but it has been refused. An accompanying error message will explain why. This code is used when requests are being denied due to update limits.
404 Not Found: The URI requested is invalid or the resource requested, such as a user, does not exists.
406 Not Acceptable: Returned by the Search API when an invalid format is specified in the request.
420 Enhance Your Calm: Returned by the Search and Trends API when you are being rate limited.
500 Internal Server Error: Something is broken. Please post to the group so the Twitter team can investigate.
502 Bad Gateway: Twitter is down or being upgraded.
503 Service Unavailable: The Twitter servers are up, but overloaded with requests. Try again later.