See the sid=167240621 part of the uri? That's your session id. That session has unfortunately expired. Oddly enough, the server gives you a 500 Internal Error response when you try to get to a page with an expired session. Since it gets a 500 response, get returns undef. Since you assign the response to $response and you later print $reponse, you get the warning. Figure out a way to get a new session and it should work as expected.