Random errors: client denied by server configuration
So this error, this little error, was the bane of existence for 3 whole days.…
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