TDOMF ERROR: Headers have already been sent in file /var/www/clients/client1/web12/web/wp-config.php on line 84 before session_start() could be called.
This may be due to...
Your current wordpress theme inserting HTML before calling the template tag "get_header". This may be as simple as a blank new line. You can confirm this by using the default or classic Wordpress theme and seeing if this error appears. You can also check your theme where it calls "get_header".
Petőfi Sándor | Kidolgozott Érettségi Tételek, Feladatok 2016