In almost all our domain name related software products, the Whois Server for PRO domains is set to whois.registrypro.pro by default. This has recently stopped working.
The correct whois server for PRO domains is now whois.afilas.net and the search token for unregistered domains is “NOT FOUND“. You can manually make the required changes by right clicking on any PRO domain and selecting “Whois Setup > Basic Whois Settings” in Windows desktop versions or “Registry Whois Setup” in the Mac OS X version.
Whois Server: whois.afilias.net
Search Token: NOT FOUND.