Cannot use session '/usr/share/gdm/greeter/gnome-session/sessions/gnome-login.session': non-existing or invalid file.

[dino99]

Found this logged after enabling debug into/etc/gdm3/custom.conf

gnome-session-binary[1073]: DEBUG(+): Cannot use session '/usr/share/gdm/greeter/gnome-session/sessions/gnome-login.session': non-existing or invalid file.

oem@ubuntu:~$ ls -l /usr/share/gdm/greeter/
total 8
drwxr-xr-x 2 root root 4096 Mar 9 13:38 applications
drwxr-xr-x 2 root root 4096 Mar 10 10:45 autostart

... the required path is indeed not found; but its not the only one:

/usr/lib/gdm3/gdm-x-session[1062]: gnome-session-binary[1073]: DEBUG(+): Cannot use session '/var/lib/gdm3/.config/gnome-session/sessions/gnome-login.session': non-existing or invalid file.

oem@ubuntu:~$ ls -l /var/lib/gdm3/.config/gnome-session/
total 4
drwxr-xr-x 2 gdm gdm 4096 Dec 2 10:17 saved-session

... the required path is indeed not found again

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gnome-session-bin 3.27.91-0ubuntu4
ProcVersionSignature: Ubuntu 4.15.0-12.13-generic 4.15.7
Uname: Linux 4.15.0-12-generic x86_64
ApportVersion: 2.20.8-0ubuntu10
Architecture: amd64
CurrentDesktop: GNOME
Date: Sat Mar 17 11:26:05 2018
EcryptfsInUse: Yes
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-session
UpgradeStatus: No upgrade log present (probably fresh install)