ubiquity-dm: starting
ubiquity-dm: plymouth
ubiquity-dm: start X ['X', '-br', '-ac', '-noreset', '-nolisten', 'tcp', '-background', 'none', 'vt1', ':0']

X.Org X Server 1.20.9
X Protocol Version 11, Revision 0
Build Operating System: Linux 4.15.0-118-generic x86_64 Ubuntu
Current Operating System: Linux xubuntu 5.8.0-25-generic #26-Ubuntu SMP Thu Oct 15 10:30:38 UTC 2020 x86_64
Kernel command line: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/xubuntu.seed maybe-ubiquity quiet splash ---
Build Date: 07 October 2020  05:46:52AM
xorg-server 2:1.20.9-2ubuntu1 (For technical support please see http://www.ubuntu.com/support) 
Current version of pixman: 0.40.0
	Before reporting problems, check http://wiki.x.org
	to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
	(++) from command line, (!!) notice, (II) informational,
	(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Sun Dec 13 12:23:30 2020
(==) Using system config directory "/usr/share/X11/xorg.conf.d"
ubiquity-dm: set vars
ubiquity-dm: pam_open_session
ubiquity-dm: dm-scripts
ubiquity-dm: start frontend gtk_ui
No such schema “org.gnome.settings-daemon.plugins.background”
No such schema “org.gnome.metacity”
ubiquity-dm: start greeter

(xfsettingsd:1545): GLib-CRITICAL **: 12:23:34.974: g_str_has_prefix: assertion 'prefix != NULL' failed

(xfsettingsd:1545): GLib-GObject-CRITICAL **: 12:23:34.986: g_value_get_string: assertion 'G_VALUE_HOLDS_STRING (value)' failed

(xfsettingsd:1545): GLib-GObject-CRITICAL **: 12:23:35.008: g_value_get_string: assertion 'G_VALUE_HOLDS_STRING (value)' failed

(xfsettingsd:1545): GLib-GObject-CRITICAL **: 12:23:35.022: g_value_get_string: assertion 'G_VALUE_HOLDS_STRING (value)' failed

(xfwm4:1538): GLib-CRITICAL **: 12:23:35.732: g_str_has_prefix: assertion 'prefix != NULL' failed
Failed to connect to session manager: Failed to connect to the session manager: SESSION_MANAGER environment variable not defined

(xfce4-terminal:34741): VTE-WARNING **: 07:37:40.163: (../src/vtepty.cc:840):void vte_pty_spawn_with_fds_async(VtePty*, const char*, const char* const*, const char* const*, const int*, int, const int*, int, GSpawnFlags, GSpawnChildSetupFunc, gpointer, GDestroyNotify, int, GCancellable*, GAsyncReadyCallback, gpointer): runtime check failed: ((spawn_flags & forbidden_args) == 0)