Problem

When you access RVsitebuilder 6 from control panel, it shows error "Sorry, None of this server IPs xxx.xxx.xxxx, xxx.xxx.xxxx, , xxx.xxx.xxxx,was found in RVGlobalsoft license system.
No details of the error"

Solution

You can verify license here: https://rvglobalsoft.com/verifyrvlicense
If it's expired, please contact your host provider to check RVsitebuilder on their license and fix it for you.