Activation Error with Unity 2017.3.1f1

I got problem installing Unity. Previously I was using 2017.2. I use free Unity Personal license. All was well. But I upgraded the Unity to 2017.3.1. I was told that I needed to reactivate the license. No problem. But I could not pass the activation process. It is said, "License file loaded successfully". But it is stuck forever. No option to move forward. I use Windows 10.

https://imgur.com/a/dCdw0

Any idea?

 

Problem solved.

1. Delete C:\\ProgramData\Unity
2. Restart
3. Install Unity again
4. Restart
5. Launch Unity

The restart steps are important.