i want to work sef url to my site.
i changed includes/sessions.php and .htaccess.
Sefurl was worked but my admin panel failed this error.
Warning: Cannot modify header information - headers already sent by (output started at /home/wwwyeni/public_html/includes/sessions.php:642) in /home/wwwyeni/public_html/admin/admin_functions.php on line 168
Warning: Cannot modify header information - headers already sent by (output started at /home/deneme/public_html/includes/sessions.php:642) in /home/deneme/public_html/admin/admin_functions.php on line 169
Warning: Cannot modify header information - headers already sent by (output started at /home/deneme/public_html/includes/sessions.php:642) in /home/deneme/public_html/admin/admin_functions.php on line 170
Warning: Cannot modify header information - headers already sent by (output started at /home/deneme/public_html/includes/sessions.php:642) in /home/deneme/public_html/admin/admin_functions.php on line 171
Warning: Cannot modify header information - headers already sent by (output started at /home/deneme/public_html/includes/sessions.php:642) in /home/deneme/public_html/admin/admin_functions.php on line 172
How can i do fix this problem?