For smooth upgrades of the MSI Package we need to add restart manager support.
I wanted to have something similar for GpgEX anyway to avoid the necessity to reboot when upgrading.
Basically Windows will send us a message like "I want to update you" and we handle that by nicely shutting down the related task is: T4748
https://stackoverflow.com/questions/51728901/wix-restart-manager-successfully-shuts-down-application-but-says-it-couldnt
https://www.advancedinstaller.com/user-guide/qa-vista-restart-manager.html