Problem Solved: upgrade.php?_wp_http_referer=%2Fwp-admin%2F

Jan 6, 2017

Recently I had a problem on a site that I manage after an auto update went bad. The result was that I could not sign into the WordPress side of the site at all. I searched for a while and was unable to find anything that worked, although I did figure out a workaround, but I wanted to fix it. Go-Daddy suggested that I back up the whole site, delete it all, and then start over. I have done that before, and I know that the headache of connecting the Database files can be arduous.

After coming across this site: http://www.vashistha.in/2016/12/problem-solved-upgradephpwphttpreferer2.html I read what he had there, and I am putting what helped me below here
(Some of it was not grammatically correct, and I have updated that here)

How I solved my WordPress websites update problem in 2 Minutes upgrade.php?_wp_http_referer=%2Fw...

upgrade.php?_wp_http_referer=%2Fwp-admin%2F

After wordpress update I was redirected to following URL and Blank Page

Here is the step by step EASY process How I solved the problem quickly

1. Open File manager of your webhosting account--This could be accessed from your cPanel for your site-->File Manager
2. Rename Plugin FOLDER to 'Plugin123'
3. In a new browser window, visit your website /wp-admin page

Your browser will automatically redirected to this page

Click on the update wordpress Database Page and once the database is fully updated go back to File manager and rename your 'Plugin' folder to 'Plugin'.
That worked well for me, and I hope it helps you too!
Thanks to Vashistha.in for the primary solution!