gnome-screensaver issue when using Wayland

[monochromec]

When using a Wayland session instead of X11 from the standard lightdm-gtk-greeter, apparently gnome-screensaver cannot establish proper GTK+ initialisation, causing the gnome-session-binary to exit and subsequently a greeter loop where a user is unable to log in.

The following is an excerpt from the syslog:

ep 12 11:06:49 darkstar-xps dbus-daemon[2031]: Activating service name='org.gnome.ScreenSaver'
Sep 12 11:06:49 darkstar-xps org.gnome.ScreenSaver[2031]: Unable to init server: Could not connect: Connection refused
Sep 12 11:06:49 darkstar-xps gnome-screensav[2165]: Unable to initialize GTK+
S

Running an identical session without Wayland produces the expected behaviour: a user can log into his desktop session and start working as usual.

Removing org.gnome.SettingsDaemon.ScreensaverProxy from /usr/share/gnome-session/sessions/gnome.session doesn't have any effect. I'm suspecting foul play between the screensaver proxy and the screensaver binary itself, but don't have the bandwidth to analyse the source at the moment.

More than happy to provide more information as required - just let me know.

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: gnome-screensaver 3.6.1-7ubuntu5
ProcVersionSignature: Ubuntu 4.10.0-33.37-generic 4.10.17
Uname: Linux 4.10.0-33-generic x86_64
ApportVersion: 2.20.4-0ubuntu4.5
Architecture: amd64
CurrentDesktop: GNOME
Date: Tue Sep 12 11:29:30 2017
GnomeSessionIdleInhibited: No
GnomeSessionInhibitors: None
GsettingsGnomeSession:
 org.gnome.desktop.session session-name 'ubuntu'
 org.gnome.desktop.session idle-delay uint32 300
InstallationDate: Installed on 2017-08-31 (11 days ago)
InstallationMedia: Ubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
SourcePackage: gnome-screensaver
UpgradeStatus: No upgrade log present (probably fresh install)

[monochromec (monochromec)]

Using gdm instead of lightdm produces a similar issue.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Christian Juner (christian-juner)]

I see the same issue on Ubuntu 17.10 on a Dell XPS 9530.

[ggalli (jack-ughetta)]

Same issue on Ubuntu 17.10 on a Lenovo B50 10.

[flapenguin (flapenguin)]

Same here. Ubuntu 18.04 on Dell E7440.
I was forced to switch to switch to lightdm, because gdm3 simply won't start.

Here're some logs:
Jul 06 00:04:07 HOSTNAME dbus-daemon[2769]: [session uid=116 pid=2769] Activating service name='org.gnome.ScreenSaver' requested by ':1.12' (uid=116 pid=2771 comm="/usr/lib/gnome-session/gnome-session-binary --auto" label="unconfined")
Jul 06 00:04:07 HOSTNAME org.gnome.ScreenSaver[2769]: Unable to init server: Could not connect: Connection refused
Jul 06 00:04:07 HOSTNAME gnome-screensav[2777]: Cannot open display:
Jul 06 00:04:07 HOSTNAME dbus-daemon[2769]: [session uid=116 pid=2769] Activated service 'org.gnome.ScreenSaver' failed: Process org.gnome.ScreenSaver exited with status 1
Jul 06 00:04:07 HOSTNAME gnome-session[2771]: gnome-session-binary[2771]: CRITICAL: Unable to create a DBus proxy for GnomeScreensaver: Error calling StartServiceByName for org.gnome.ScreenSaver: GDBus.Error:org.freedesktop.DBus.Error.Spawn.ChildExited: Process org.gnome.ScreenSaver exited with status 1
Jul 06 00:04:07 HOSTNAME gnome-session-binary[2771]: CRITICAL: Unable to create a DBus proxy for GnomeScreensaver: Error calling StartServiceByName for org.gnome.ScreenSaver: GDBus.Error:org.freedesktop.DBus.Error.Spawn.ChildExited: Process org.gnome.ScreenSaver exited with status 1

[Jerry Quinn (jlquinn)]

I see this on Ubuntu 18.04 as well, but I have a gnome-based gui that works. Here's my log snippet:

May 26 12:23:47 cerberus org.gnome.ScreenSaver[2217]: Unable to init server: Could not connect: Connection refused
May 26 12:23:47 cerberus gnome-screensav[2263]: Cannot open display:
May 26 12:23:47 cerberus dbus-daemon[2217]: [session uid=130 pid=2217] Activated service 'org.gnome.ScreenSaver' failed: Process org.gnome.ScreenSaver exited with status 1
May 26 12:23:47 cerberus gnome-session[2223]: gnome-session-binary[2223]: CRITICAL: Unable to create a DBus proxy for GnomeScreensaver: Error calling StartServiceByName for org.gnome.ScreenSav
May 26 12:23:47 cerberus gnome-session-binary[2223]: CRITICAL: Unable to create a DBus proxy for GnomeScreensaver: Error calling StartServiceByName for org.gnome.ScreenSaver: GDBus.Error:org.f