Unity License Error

Hy! I changed my windows from 10 to 7 and after 3 days of using Unity I got License Error.

I cant hit the Re-Activate button, I also tried to sign in but when i clicked this button twice(because for the first click nothing is changed) i got this blank window.

After that i cant do anything, when I close this window and re-open Unity, I get again the License Error.
Anyone knows what is this problem and how can I fix it?

I have exactly the same error, but haven’t changed OS, currently using win10.

Edit: I fixed it by doing the manual activation, getting inside the proyects menu offline, re enabled wifi and logged in.

Edit: its bugged again.