I have successfully upgraded to 2.2.0. But the websetup wizard is not opening at all.
It is getting stuck like this http://prntscr.com/gqyuw2
Issue resolved itself for me. Turns out cron just needed a few more minutes to run and complete its setup, despite being told the setup had completed. Leaving it for 10 minutes or so (can't remember how long cause I was Googling an answer), when I went back both installations have fixed.
Scratch that - It's a cookie issue. Just ran into the same problem again. Opening a session Incognito immediately fixed it. I would suggest completely clearing session cookies in your browser if you run into this again.