When attempting to log into the Debian Desktop image with the username and password ‘rock’ via UART, I get this:
localhost.localdomain login: rock
Password:
Login incorrect
localhost.localdomain login:
Is the default username/password for this image different from the Ubuntu Server one? That username and password worked fine there.
If you got image from https://github.com/armbian/community then its root / 1234
I got the image from https://wiki.radxa.com/RockpiN10/downloads, the Debian Buster section.
it should be rock/rock, but for some images there was radxa/radxa or root/root or someething with one of those names but no password.
Also pay extra attention if You connection settings are correct