Thank you for your reply.
It is supposed to be installed, and working. I didn’t do anything to the ACF plugin before the error appeared. All I did was deleting a translated version/copy of the main parent page.
It is supposed to be installed and active: http://d.pr/i/kA9K
The translation of the page “Velkommen” is the one I deleted: http://d.pr/i/oWvW
Would you suggest I reinstall the ACF plugin, or something similar? Or anything else?
