500 Error on wp-admin after upgrade
This happened with one of our individual installs and it’s happened before (but I forgot the solution) so I’m writing it down.
After the upgrade to 4.7.1, the front of the sight still worked but attempts to get to wp-admin failed with a 500 error and the URL was redirecting to something with upgrade.php? in the URL.
Change the name of the plugin folder (I just prepend an underscore).
Revisit your login URL.
Run the database upgrade as prompted.
You should now be in the admin zone.
Fix your plugin folder name.
Easy but also easy to forget.