Parallels 26 Won't Activate

I installed Parallels 26 but it won't activate. When I click Activate it gives me an error "Unable to verify the license signature." If I click the Enter a new key button, I can enter my key and the green check mark displays, but when I click Activate, I get the same error message. I can't get into any of my VMs.

 

Same here. I've tried to start Parallels and i have activation error - "Unable to verify the license signature."

 

I had the same with one license key while another key worked fine. Today both keys work fine, but not sure if someone fixed something since I created a ticket about the problem yesterday.