Hello
bw123. Thank you for your suggestions.
It doesn’t look like I’m using lightdm or sddm.
There is no “lightdm” directory under /etc.
There is a “sddm” directory, but it only contains “Xsession”.
Running “kcmshell4 —list” gives 13 lines of error messages starting with…
“kcmshell(2390)/kdeui (kdelibs): Session bus not found”and ending with…
“Not forwarding the crash to Apport.”Running “kcmshell5 —list” outputs
“The following modules are available:”, followed by a long list of “modules”. sddm is not included in the list.
Hello
piper. Thank you for your suggestions.
As mentioned above, there is no sddm.conf file under /etc, so I created one based on your default example, changing MinimumUid to 501.
Damn! It works! 
Will now continue with the rest of my installation to see if everything else works as expected, (as in Debian_8).
Thank you bw123 & piper!FYI: Installation to this point was mostly default…
- Used a debian-9.6.0-amd64-netinst.iso CD.
- Partitioning scheme was with separate /home, /var, and /tmp partitions.
- Installed Debian Desktop Environment, KDE, SSH server, Standard system utilities.
- Also installed autofs, nfs-kernel-server, nfs-common, ntpdate, csh, tcsh.
- Updated UID_MIN & GID_MIN values in /etc/login.defs to 501
- Updated FIRST_UID & FIRST_GID values in /etc/adduser.conf to 501