Update: It seems I fixed it.

Now I hate people who post “solved” without telling other people how, so I won’t be one of those people:

I was reading other threads, with similar problems, in one of them someone said “4.3 broke my site”. Moderator Yigit replied telling the user to delete that file.

I decided to do the same, I deleted the file ” events_upcoming.php”, which is found in /wp-content/themes/enfold/config-templatebuilder/avia-shortcodes/events_upcoming/.

It worked! :)

So for now, you can mark this as solved.