While updating Parallels RAS from version 15.5 or older to version 16.0 or newer Remote PC Agents remain not updated even though MSI installation operation is successful.
Checking Remote PC Agent status will show that Remote PC Agent component version is still the same as it was before upgrading attempt.
Such behavior is by design limitation as Remote PC Agent component is designed only for Client Operating Systems such as Windows 7, Windows 8.1, Windows 10. Starting from Parallels RAS version 16.0 product installation package performs operating system check before installing the component. If Remote PC Agent component is installed on machine running Server operating system installation will not be possible.
Please note: Installing Parallels RAS Remote PC Agent component on machines running Server operating systems was possible with Parallels RAS version 15.5 and older versions since MSI package was not performing operating system check. Regardless of this possibility such setup is incorrect due to performance mechanism of Remote PC Agent component which is designed specifically for Client Operating Systems that allow only one simultaneous remote connection.
In order to publish resources from machine running Server Operating System please use Parallels RAS RD Session Host component.
Important note: As Parallels RAS RD Session Host component serves to deliver resources from terminal servers Microsoft RDS CALs must be installed on all Terminal Servers from which resources will be published. For assistance with Microsoft RDS CALs purchase, installation, and configuration please contact Microsoft Support Team.