Please try to remove and re-install the pre-requisites. Make sure you install the newest version.
We just upgraded our XWS server from 5.1 to 126.96.36.199 and since then I can't add printers anymore. Choosing the repair option will also end in an error, removing Mobility Suite from the printer
When trying to add or manage a printer using the admin web page, the "There was an error processing your request or the system was busy. Please try again later." is received.