MacOS Installation Couldn't be completed.

Mac Pro mid 2010 / High Sierra ( Not sure what version )

Today I restarted my Mac Pro because my internet was acting slow and it automatically started installing updates. Now I have the dreaded macOS installation couldn't be completed screen.

The last time I took a time machine snapshot was right before I installed High Sierra. I dont think I can go back to that because the SSD is in a different format, is that correct? I dont even know what updates were being installed. Could it be it was trying to install Mohave?

What are my best options for installing or fixing macOS from here. Will I loose all my apps, fonts, files ?

Thanks!