Everyone is giving a bunch of mumbo jumbo explanations regarding re-entering the activation code and firewalls and all of that mess. Here's how I solved the problem. DO NOT RE-ENTER the activation code. Hit cancel and close the program. Re-open it several times and hit cancel DO NOT enter the activation code. Then shutdown your computer. Turn it back on. Open TT 2019 if it asks for the activation code DO NOT enter it keep cancelling and closing the program. It took me at least 5 open and closes and one shutdown then opened it two more times and it worked. I have had to do this almost every time I close the program and come back to it later or a different day.
