So the problem is solved. the Hosting is working on a fix for a problem with "sessions_start() " of PHP. At this moment, i have a tempory fix, and the...

Removing Cache plugin Folder doesn't work. I 'll wait for my request from my host, and ask a backup. Thank you Robert, and Anonymous20 for your help....

Yes i checked the server disk space : 1,41 GB / 146,48 GB. I just send a request on to my host I gonna remove the cache plugins and check if it fix ...

ok, so when i remove WPforo i got this message Warning: session_start(): open(/var/cpanel/php/sessions/ea3/sess_9c812f926777a5b7eb56aec6ce563e15, O_RD...

ok, i test this, and i come back

and yes , it's sudden, there are 2 days ago, the website works fine. I didn't make any update.

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

Ok thank you for this comment. I'll try to contact my hosting webiste. Thank you, and have a nice day.