Hi, I installed Debian 10.0 ("Buster"), the current stable Debian release since some days, on my testing machine using a Netinstall CD.
During the installation process I deactivated the installation of Gnome and instead activated the installation of KDE Plasma. So this installation is no upgrade from Debian 9.x ("Stretch"), but a new installation. My testing machine has no Nvidia hardware. I did not install Debian Buster into an instance of Virtualbox. Debian Buster starts successfully but does not present a login manager to KDE at the end of the boot/start process. Instead the console is shown on tty1. Until here no /var/log/Xorg.0.log gets created. If I enter "startx" as root or the normal user in the console, then KDE starts successfully. The package sddm is installed. The file /etc/X11/default-display-manager contains "/usr/bin/sddm". I have an AMD Radeon graphic card, i.e. a Radeon HD 4350/4550. Installing the package firmware-amd-graphics (thanks for this hint to user towo from an Internet forum) does not resolve the behaviour. The command "journalctl | grep sddm" (thanks for this hint to user MSfree from an Internet forum) results in the following output ("startx" has not been executed before): --- Quote Beginning --- root@xxx:/home/yyy# journalctl|grep sddm Jul 09 13:16:06 shit sddm[401]: Initializing... Jul 09 13:16:06 shit sddm[401]: Starting... Jul 09 13:16:06 shit sddm[401]: Logind interface found root@xxx:/home/yyy# --- Quote End --- The command "systemctl enable sddm" (thanks for this hint to user wanne from an Internet forum) results in the following output: --- Quote Beginning --- Synchronizing state of sddm.service with SysV service script with /lib/ systemd/systemd-sysv-install Executing: /lib/systemd/systemd-sys-install enable sddm The unit files have no installation config (WantedBy=, RequiredBy=, Also=, Alias= settings in the [Install] section and DefaultInstance= for template units). This means they are not meant to be enabled using systemctl. Possible reasons for having this kind of units are: - A unit may be statically enabled by being symlinked from another unit's .wants/ or .requires/ directory. - A unit's purpose may be to act as a helper for some other unit which has a requirement dependency on it - A unit may be started when needed via activation (socket, path, timer, D- Bus. udev, scripted systemctl call ...) - In case of template units, the unit is meant to be enabled with some instance name specified. --- Quote End --- Regards, Jens