Hi @LP_10027711.
As we found while working the case, the cause of the upgrade failure was due to the database host being changed after the initial ThingWorx installation. This prevented the installer from connecting. The original installation information is located in \ThingWorxFoundation\twxfoundation_report.json. This file had to be updated with the correct db hostname in order for the installer to run successfully.
If you agree that this was the cause of the issue, please mark this response as the Accepted Solution for the benefit of others with the same issue.
Regards.
--Sharon