I ran into this trying to access a Raspberry Pi using UltraVNC on Windows 10. The solution is to go into the VNC Connect Options on the Raspberry Pi desktop, on the first tab "Security" change the Authentication from UNIX password to VNC password. You will then be prompted to set the VNC password.
I'm sure this can be done by modifying a config file from ...
I installed on the smart card the Debian VERSION="10 (buster)". There is no Display connected to the Raspberry. I'm connected it only through it's Ethernet (UTP-cable), and the wifi module is disabled. I edited as sudo the /boot/config.txt file to disabble the wifi loading on boot.
# wifi off / dissable
# change on 10-08-2019