For some reason, if an upgrade of an AppAssure/Dell Rapid Recovery Agent is not succesfully completed or cancelled, a subsequent upgrade may fail with the following error message:
If an upgrade was cancelled or has failed for some reason, the following upgrade attempt will try to perform a complete installation. Because not all files and/or folders have been removed, the installer will not continue and will display the error message.
To resolve the problem, manually remove the files and folders, but leave any registry keys intact to ensure a proper upgrade without losing any settings.
Note that this error can also occur when upgrading a Core server. The same method to resolve the problem applies but it is recommended to backup the registry key HKEY_LOCAL_MACHINE\Software\AppRecovery before re-running the installer.