Cinnamon session crashing login from greeter

Solution 1:

The key were these parts of the message: GLib-GIO-ERROR and Settings schema 'org.gnome.desktop.file-sharing'

Where does GLIB store its schemas?

/user/share/glib-2.0/schemas/

$ cd /user/share/glib-2.0/schemas/
$ grep file-sharing *
Binary file gschemas.compiled matches
org.gnome.desktop.file-sharing.gschema.xml:<schema path="/org/gnome/desktop/file-sharing/" id="org.gnome.desktop.file-sharing" gettext-domain="gnome-user-share">
$ dpkg -S /usr/share/glib-2.0/schemas/org.gnome.desktop.file-sharing.gschema.xml
gnome-user-share: /usr/share/glib-2.0/schemas/org.gnome.desktop.file-sharing.gschema.xml

Aha - gnome-user-share looks like the culprit!

What does gnome-user-share do?

$ apt search gnome-user-share
Sorting... Done
Full Text Search... Done
gnome-user-share/bionic,now 3.18.3-3 amd64 [installed]
  User level public file sharing via WebDAV

I do not need User level public file sharing via WebDAV, so I will remove it.

$ apt-get purge gnome-user-share

I rebooted the computer and was able to login to a nice Cinnamon desktop.

_{Time to go make some Cinnamon Toast. Does anyone have a good recipe for that for that? ;-)}