hum i haven't access to my admin account on the website, so i can't remove WpForo. So i can't test if that work without Wpforo
No need to admin your site. FTP and remove (for a while) the wpForo plugin folder. carefully.
and yes , it's sudden, there are 2 days ago, the website works fine. I didn't make any update.
Then your provider changed/updated something.
ok, i test this, and i come back
ok, so when i remove WPforo
i got this message
Warning: session_start(): open(/var/cpanel/php/sessions/ea3/sess_9c812f926777a5b7eb56aec6ce563e15, O_RDWR) failed: No such file or directory (2) in /home/umbrafra/public_html/wp-content/themes/robot/functions.php on line 19
Warning: session_start(): Cannot send session cache limiter - headers already sent (output started at /home/umbrafra/public_html/wp-content/themes/robot/functions.php:19) in /home/umbrafra/public_html/wp-content/themes/robot/functions.php on line 19
so the problem, is not Wpforo.
I've already explained that in my last post, this is not wpForo issue. Please read it again. Have you checked your server disk space?
Also disable all cache plugins, delete the cache plugin folder in plugins directory, this maybe cache plugin issue as well.