Unable to activate Parallels Desktop: 'Unable to perform the operation' error message

Symptoms

Parallels Desktop cannot connect to the Internet to validate the license. Unable to perform the operation error message pops up.

Cause

• Your Mac is not connected to the Internet
• All Parallels Desktop outgoing connections are blocked by a firewall
• Your Internet connection uses proxy

Solution

• Make sure your Mac is connected to the Internet.
• Ask your system administrator if your Mac has any active network connections behind Proxy. Disable Proxy and try to activate Parallels Desktop again.
• If you have any Firewall software installed on your Mac like Sophos, LittleSnitch or built-in macOS Firewall, create an exception for Parallels Desktop application so all outgoing connections are allowed.
• Make sure Parallels Desktop outgoing connections are not redirected.