I’m following up to the original post because I didn’t realize that there was a reply and the topic had been closed. My initial question is located here. https://theme.co/forum/t/problem-editing-cornerstone-pages-after-upgrading-x-theme/80309.
I’ve tried turning off all the non-x theme plugins and still get the error and we aren’t running a child theme. I’ll list my login details below for you to please check what might be happening to the site.