I’m facing this very problem with my WordPress after upgrading and I turned to the Internet for solution. Lo and behold I wasn’t alone. There’s many out there similar to me who faces the same problem.
It seems there’s a likely plugin issue. I didn’t zero it down which plugin it was, but took a quicker solution by downloading a plugin that fixed my problem.
Download Your attempt to edit this post has failed Plugin Fix
or you can also
remove “
wp_enqueue_script('autosave');” code from wp-admin/post-new.php
