I upgraded my system to Debian 12, but I cannot login any more after I rebooted when the package installation seemed to be completed. The login prompt (on tty) tells me login incorrect after typing any (even empty, even root) string with my keyboard and finishing it with Return (standard way to type in a user name).
Sometimes the issue in comparable situations is because there's no space left on the device. I'm pretty sure I can exclude this as a possible reason here because I cheked that every partition has at least several MB of free space with gnome-disks from a live system.
The screen at Ctrl+Alt+F7 is stuck at [ OK ] Started Anonymizing overlay network for TCP. with a blinking underscore cursor in the line under the fullstop. The line breaks don't work correctly as it seems to add the space of a whole line to do the line break, not just breaking the line and starting at position 0 for writing the next line.
I'd like to not reinstall my system in order to use it again.
Ctrl+Alt+F1 as well as Ctrl+Alt+F3 behave in the same manner:
Debian GNU/Linux 12 hosti tty3
hosti login: root
Login incorrect
hosti login: _
I'd like to not need to reinstall Debian because I did lots of customisations, which I cannot list all anymore and therefore I'd looking forward to fixing my broken login (or system) way more than reinstalling the system.
EDIT Side observation: Trying to take an empty username for login doesn't succeed for the first attempt on the screen, but for the other ones. I also can only take four attempts "once"; the screen "clears" after the fifth attempt.
"Four attempts":
Debian GNU/Linux 12 hosti tty3
hosti login: number1
Login incorrect
hosti login: number2
Login incorrect
hosti login: number3
Login incorrect
hosti login: number4
Login incorrect
hosti login: numberFIVEwhichIStheLASToneSEENonTHEscreenAFTERthisONEtheSCREENseemsTOclearORrefreshAUTOMATICALLYafterEXAMININGtheATTEMPTtoLOGin_