I tried to edit a page on my site today and got an error suggesting there was an error in my HTML markup. I checked the code and it was fine so I went to a different page and the same error. I then tried creating a brand new page with no content on it at all, start from scratch, and again it threw up the error.
I note from searching the forums that the advice when someone had an issue with X, 6 and Cornerstone was to make sure the latter was up to date. I took a look to see if I could find some way of following those instructions but I can’t find a way to delete & reinstall cornerstone so I’ve been unable to try that.
I’ve not added any new plugins. Quite transparently, it’s been a couple of weeks since I’ve needed to edit anything so I don’t know exactly when this problem started. I can see that the site auto-updated to Wordpress 6 relatively recently which is why I’m wondering if this might be causing the issue.
I’ll attach some screengrabs so you can see what I’m getting. Everything is up to date. Thank you in advance for your help 



