If you see me reply above and get the same error message, here is an approach

All workstations worked fine but Server/Workstation failed after allowing updates. Earlier updates worked fine. The program works fine except for 2019 Product Updater. Previous years all work fine.

Problem in this case was a silent update of a new feature in Backup program which is some sort of malware detector. Only ProSeries 2019, not any earlier years, caused the updater app to fail.

Boot into Safe Mode with Networking (So you can log into ProConnect)

https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode

Run the stand alone ProSeries Update applet from ProSeries 2109 program group. If it works then

use normal troubleshooting process to identify the culprit

https://support.microsoft.com/en-us/help/929135/how-to-perform-a-clean-boot-in-windows

Hope it helps