HTTP Response Codes

Code Explanation
200 OK Request was successful.
201 Created Creation of the resource was successful.
204 No Content No error. Used when the server does not need to return any information in the response entity. Metadata about the request maybe returned in response headers.
304 Not Modified The resource hasn't changed since the client's last read. This could be driven off If-Modified-Since header or Etag. Assuming each entry has an updated date, If-Modified-Since probably makes more sense.
400 Bad Request Returned under the following conditions:
  • Invalid request URI.
  • Invalid request header.
  • Receiving an unsupported non-standard parameter.
  • Invalid parameter values are also included.
401 Unauthorized Authorization required.
403 Forbidden Unsupported standard parameter, or authentication or authorization failed.
404 Not Found Resource not found.
405 Method Not Allowed The method specified in the request is not allowed for the resource.
409 Conflict The request could not be completed due to a conflict with the current state of the resource. For example, a client attempts to update an old version of a resource.
410 Gone The requested resource is no longer available at the server and no forwarding address is known. This condition is expected to be considered permanent.
412 Precondition Failed A precondition given in a request header evaluated to false. For example, a PUT request with a If-Unmodified-Since header might return a 412 if a resource was updated after the value of the If-Modified-Since header.
415 Unsupported Media Type The server is refusing to service the request because the entity of the request is in a format not supported by the requested resource for the requested method.
500 Internal Server Error The default status code used for all unrecognized server errors.
503 Service Unavailable The server is currently unable to handle the request due to a temporary overloading or maintenance of the server.


Web services will include a descriptive message in the HTTP response entity when returning a HTTP 4xx and 5xx status code.