session_start(): cannot send session cache limiter - headers already sent, warning in the same php file

<?php session_start(); 

If your php server cribs that the error is in line 1 (<?php) and you have tried every debugging technique to solve the mystery without success... then the last tip could be: 

Recreate this file in a basic text editor like notepad as 'ASCII' file and upload it. 

If it still doesn't solve your problem then you need to dial God! 

DVM, 

~ Idea Naren