The column hide_from_media_manager
was renamed to hidden
in FoF Upload v1.5.
Based on your log file, the error Column not found: 1054 Unknown column 'hide_from_media_manager' in 'where clause
seems to happen during a regular API request and not the activation, likely when the user attributes extender retrieves the count for the relation User::foffilesCurrent
which itself filters by that column.
We don't see FoF Upload in your php flarum info
output above, but I suspect you installed FoF Upload 1.5+ at some point but now have a version <1.5 installed, which fails to boot when it doesn't see the old column name.
Flarum extensions (and their database in particular) are not designed to be downgraded. You need to install FoF Upload 1.5+ or revert to a backup from before you updated the database if you wish to stick on an older version.