I'm coming back to the forum as I couldn't fix my issue: images and files are still not accessible from within the wiki, and I even don't know where they're supposed to be stored.
The wiki is running from /var/www/vhosts/bcasmart.com/httpdocs/tw.
Data are (supposed to be) stored in /media/diskext/tw.
How can I query the system to find which user/group is authorized on the wiki folder? Maybe duplicating the same access rights to the data folder would solve the issue...
I've also checked that PHP is allowed to read/write into the data folder: I've updated the open_basedir variable to include the data folder path. Is this requested? Is this enough?
Wiki is still returning "File upload failed:" with no error code or message when trying to upload a file or a picture. Unfortunately, configuring wiki to store files into the database leads to the same result!
I'm feeling despaired and am missing the necessary system skills to understand how to troubleshoot...
Thanks in advance for any help!