Look at all the other posts stating the same thing. After they upgraded they have problems logging in.
That points to a bug….
As stated I have done everything suggested to clean the cookies etc. Still can’t login. Get the message to log in again and again.
This is a bug. And it’s quite silly that nobody from the development team has commented on this bug. After 3 days.
No matter how you twist and turn it. It’s still a bug. A bug that many people has reported but nobody from the wordpress team has commented on.