Add / Change dns – CentOS
The easiest to add or edit the dns servers your server uses is to edit…
The solution two this error is one of two things, either session create is not checking for an existing session before starting one, or the php.ini has session.auto_start enabled.
Make sure you create a session by checking if one doesn’t already exist:
If you are sure this has been set properly then the following could be the solution:
Restart apache / php-fpm and see whether this solves your problem