I get this problem and I can't solve it. At the following logout.php script . 
<?php
session_start();
error_reporting(E_ALL ^ E_NOTICE); 
ini_set('display_errors', 'On');
session_destroy();
 header('Location: index.php');  
exit;  
?>
Always I get this:
Warning: Cannot modify header information - headers already sent by (output started at /home/traningi/public_html/logout.php:3) in /home/traningi/public_html/logout.php on line 11
I try some things but doesn't work
 
     
     
     
    