I think I got this right and I just want to share what happened. I was upgrading, but I walked away and let it run. When I came back the screen was black with a flashing underscore in the upper left corner. I waited a few minutes, nothing, so I tried the usual tricks to return it to life, nothing again, so I powered it off. When it came back up, it seemed to mostly work, but it couldn't load Gnome and it gave me a white screen announcing that it had failed and I needed to log off and try again. I did that and got to the login screen, but after that I couldn't log in -- it always went back to the white fail screen. Then I searched the web and found this: How To Fix Broken Ubuntu OS Without Reinstalling It https://www.ostechnix.com/how-to-fix-broken-ubuntu-os-without-reinstalling-it/ I could ssh into the box, so I did it that way, using copy/paste from the web page. And it seemed to work. In case someday that web page is gone, these were the commands: sudo rm /var/lib/apt/lists/lock sudo rm /var/lib/dpkg/lock sudo rm /var/lib/dpkg/lock-frontend sudo dpkg --configure -a sudo apt clean sudo apt update --fix-missing sudo apt install -f sudo dpkg --configure -a sudo apt upgrade sudo apt dist-upgrade sudo reboot After that it worked perfectly. For some reason the time was not being set automatically, so I went here... Settings > Details > Date & Time ...and activated "Automatic Date & Time". That fixed it. I think I'm all set, but let me know if you see anything wrong with those commands. Is there anything more I need to do? Thanks in advance. Mike