I have been having a problem with one of my Wordpress blogs that had me stumped: Whenever I would comment on it, being logged in as my Wordpress user, I would get the error message:
"please fill the required fields (name, email)."
This started happening out of nowhere, without any connection to an update as far as I could tell. I even went so far as to check the code of my child theme - nothing. And I could not find any matching posts on the Wordpress forums either...
It turned out to have a very simple solution. I disabled Jetpack, re-enabled it, and authorized Jetpack with Wordpress.com again and lo and behold, the problem is gone.
No idea what the actual cause was, but this was one solution I did not try for some time - so I hope this helps anybody who is similarly stuck. ;-)