If you make an ajax request of type jsonp, and the response is an http-204 response code (which specifies no body content), neither the success nor the error handler are called.

I stepped through a debugger with jquery 1.4.4, and hit this code.

6000 // Make sure that the request was successful or notmodified
6001 if ( status === "success" || status === "notmodified" ) {
6002     // JSONP handles its own success callback
6003     if ( !jsonp ) {
6004         jQuery.handleSuccess( s, xhr, status, data );
6005     }
6006 } else {
6007     jQuery.handleError( s, xhr, status, errMsg );
6008 } 

It appears that if the status is a success, and it is not a jsonp request, nothing happens -- after stepping through a bit more the function simply returns.

Earlier during the global eval, since it is a 204 response, data = "", and thus there is no jsonp callback function named to call.

Is this expected behavior? I would think in the case of a jsonp request, if there is no content (and thus no function named to call back into), the error handler should be called.