Security Update 2020-001

When trying to install this update for High Sierra 10.13.6 (Mac Pro 5,1) the computer attempts to shutdown, the screen goes black indefinitely, but it never actually shuts down or updates. A hard reboot gets the machine back on and running. However, any attempts at completing the update or even trying to do a standard shutdown/restart result in same problem. The computer simply not longer shuts down properly.

Standard troubleshooting tools like Reset Pram do nothing.

I was able to resolve the issue and restore the computer to proper working order by eliminating the current 2020-001 update process via the following terminal command.

sudo rm -f /Library/Preferences/com.apple.loginwindow.plist
sudo rm -f /private/var/db/.AppleUpgrade
sudo rm -f /private/var/db/.SoftwareUpdateAtLogout
sudo reboot

This fix was authored by nohillside.

Apple please let me know when this security update won't break my computer, much thanks !!!