Problem solved, i used a plugin to set different themes for my forum's pages. Thank you all for helping me!

Posted by: Anonymous20 Posted by: dilu93 Posted by: Anonymous20 Well if it is your theme, them the author of the theme can help you. ok thanks, i'l...

Posted by: Anonymous20 Well if it is your theme, them the author of the theme can help you. ok thanks, i'll try to contact the author, meantime can...

Posted by: Anonymous20 1. Switch to WP Default theme. 2. Disable ALL plugins BUT wpForo. 3. Check if it works. 4. If it works, switch to your theme. 5...

Posted by: Robert As far as i see the problem comes from WooCommerce plugin. It seems you have a copy of WooCommerce plugin template file in current W...

Posted by: Anonymous20 You can start by TOTALLY remove and delete the [--moderated--] W3 Total cache. I'm shocked that people use that useless monster...

Posted by: Robert Please delete all caches, and disable all features of W3 Total Cache plugin. This maybe a cache conflict. If it doesn't help, disab...

Posted by: Sofy Hi dilu93, The issue is related to TinyMCE, that is not defined. Please deactivate all Optimizer and Minifier plugins, delete all cach...

Thank you for your help, but i can't understand the first part, which plugin i have to deactivate?I think i don't have neither optimizer or minifier p...