This error typically occurs when a user already has a registered server.
VyprVPN Licensed Server Edition owners and admins will be able to register one VyprVPN Licensed Server, with the ability to purchase additional Server licenses from the account portal if additional VyprVPN Licensed Server instances are needed.
To remedy this error, follow the steps here - How do I deregister a server
If that does not resolve the issue, or you haven't previously registered a VyprVPN Server, reboot the server from the System Settings section in the web administration panel and try again after it comes back online.
If you need any further assistance, please contact our 24/7 Customer Success Team, who would be glad to assist.