This error sometimes happens when installing the riteSCAN Administration Application. Generally it is because a client application is accessing the Web Service and the installer is not able to un-register the 8300 or 8301 port through UltiDev.
To solve this issue it is recommended to uninstall the Administration Application and re-install it, this will allow the port registration to properly complete.
Another cause of this error is if you have riteSCAN Admin installed under IIS and you're now running the UltiDev installer from the installation splash screen. IIS is already using the port that the UltiDev installer is trying to use. The solution here is to install the IIS version of the Administration and not the UltiDev version.
