Blank page with cursor when launching greeter

[pescepalla]

Here's the output of the lightdm --test-mode --debug command:

[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log [+0.00s] DEBUG: Starting Light Display Manager 1.32.0, UID=0 PID=14219 [+0.00s] DEBUG: Loading configuration dirs from /usr/share/lightdm/lightdm.conf.d [+0.00s] DEBUG: Loading configuration dirs from /usr/local/share/lightdm/lightdm.conf.d [+0.00s] DEBUG: Loading configuration dirs from /etc/xdg/lightdm/lightdm.conf.d [+0.00s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf [+0.00s] DEBUG: Using Xephyr for X servers [+0.00s] DEBUG: Registered seat module local [+0.00s] DEBUG: Registered seat module xremote [+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager [+0.00s] DEBUG: _g_io_module_get_default: Found default implementation local (GLocalVfs) for ?gio-vfs? [+0.01s] DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3) [+0.01s] DEBUG: Monitoring logind for seats [+0.01s] DEBUG: New seat added from logind: seat0 [+0.01s] DEBUG: Seat seat0: Loading properties from config section Seat:* [+0.01s] DEBUG: Seat seat0 has property CanMultiSession=no [+0.01s] DEBUG: Seat seat0: Starting [+0.01s] DEBUG: Seat seat0: Creating greeter session [+0.02s] DEBUG: Seat seat0: Creating display server of type wayland [+0.02s] DEBUG: Could not run plymouth --ping: Failed to execute child process ?plymouth? (No such file or directory) [+0.02s] DEBUG: Using VT 7 [+0.02s] DEBUG: Seat seat0: Display server ready, starting session authentication [+0.02s] DEBUG: Session pid=14227: Started with service 'lightdm-greeter', username 'lightdm' [+0.02s] DEBUG: Acquired bus name org.freedesktop.DisplayManager [+0.02s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0 [+0.02s] DEBUG: Loading users from org.freedesktop.Accounts [+0.02s] DEBUG: User /org/freedesktop/Accounts/User1000 added [+0.02s] DEBUG: User /org/freedesktop/Accounts/User1001 added [+0.04s] DEBUG: Session pid=14227: Authentication complete with return value 0: Success [+0.04s] DEBUG: Seat seat0: Session authenticated, running command [+0.04s] DEBUG: Session pid=14227: Running command /usr/bin/cage -m last -s -d elephant-greeter.py [+0.04s] DEBUG: Creating shared data directory /var/lib/lightdm-data/lightdm [+0.04s] DEBUG: Session pid=14227: Logging to /var/log/lightdm/seat0-greeter.log [+0.05s] DEBUG: Activating VT 7 [+0.07s] DEBUG: Greeter closed communication channel [+0.07s] DEBUG: Session pid=14227: Exited with return value 1 [+0.07s] DEBUG: Seat seat0: Session stopped [+0.07s] DEBUG: Seat seat0: Stopping; failed to start a greeter [+0.07s] DEBUG: Seat seat0: Stopping [+0.07s] DEBUG: Seat seat0: Stopping display server [+0.07s] DEBUG: Seat seat0: Display server stopped [+0.07s] DEBUG: Seat seat0: Stopped [+0.07s] DEBUG: Required seat has stopped [+0.07s] DEBUG: Stopping display manager [+0.07s] DEBUG: Display manager stopped [+0.07s] DEBUG: Stopping daemon [+0.07s] CRITICAL: instance with invalid (NULL) class pointer [+0.07s] CRITICAL: g_signal_emit_valist: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed [+0.07s] DEBUG: Releasing VT 7 [+0.07s] DEBUG: Exiting with return value 1