Google account fail

I updated to the 6.3.41 firmware. Since then, I get this answer if I want to log in:

Failed to add account. Try again.

First i fixed the “This device is not Play Protect certified” error. I enter the account name, then the password, but I always get this message. There has also been a restart twice. Moreover, the factory reset as well. Of course, the datas are correct. I don't understand.

 

Try add GSF ID again factory reset generated a new once.
https://www.google.com/android/uncertified/

 

Thanx, but I registered after a factory reset the ID.

 

Now another FR, another ID number registration, same problem I can't belive it! The YT login works, but the Google account login failed.

 

Maybe off the wall but what about clearing your cookies if there are any?

 

After FR the cookies are cleared to. But unbelievable, passed the second login attempt after the third FR. I don't understand what happened. I hope not all firmware update like such!