Hi, I upgraded to 2.0.2 on two computers. After the upgrade, I was asked to Authenticate but Syncthing would not accept my credentials - even though they were saved in the browser. (Not very secure, I know.)
As for recovering: you can recover from the need for a password by manually editing the config file and removing the gui→password item. Restart syncthing, then open the gui, then set a password again.