I had been using php version 5.2 and everything was working fine but when I upgraded to version 5.5 I started getting a warning saying:

Warning: session_start(): Cannot send session cache limiter - headers already sent

This doesnt make any sense to me as I do not have any output prior to calling the session_start() and also why would I get this warning with php 5.5 and not with 5.2? This is how I start all of my pages:

PHP Code: