I just did the update the other day and now I find that I am having trouble entering cornerstone for my website pages. I have included a picture of the error message.

is it something with the upgrade? I have also been trying to work on improving the caching on the website, so perhaps its another plugin I downloaded thats blocking cornerstone?
any help would be greatly appreciated, the site is live now and not being able to edit my pages at all is kind of a big block in the road.
thank you.