UPS WorldShip 2017 upgrade to 2018 fails

[problem]

UPS WorldShip 2017 running on Windows 7 SP1 fails to upgrade to UPS WorldShip 2018 when the upgrade is performed via the in-application upgrade button due to the following error:

[solution]

1. Backup UPS WorldShip database.
2. Uninstall UPS WorldShip 2017
3. Visit C:\UPS\WSTD\Autodownload\TEMP\ and run setup.exe if it exists there. NOTE: This will be the already extracted install for UPS WorldShip 2018 which failed due to the error. When you run the setup.exe manually though, it just installs without errors.
4. Reboot when prompted.