I am receiving this error when opening the editor, going to content, and clicking edit on a page.
I applied the solution to alter my functions.php with :
add_filter( 'w3tc_can_print_comment', '_returnfalse' );
That hides the error, but the content editor still won't work. I have errors in my console that say:
POST http:///cornerstone-endpoint 500 (Internal Server Error)
Please advise why I can not edit ANY pages in the content editor. I can provide login info to my site if needed.