I was able to get around the below errors by deleting the user’s .x2go directory. Any reason why this continues to happen? We’re using the nightly builds. Here are some logs. Fails with MATE and XFCE.

rpm -q x2goserver

x2goserver-4.1.0.0-0.0x2go1.0.git20171015.1421.heuler.fc26.x86_64

 Unable to contact settings server
 Failed to connect to socket /run/user/xxxx/bus: Connection refused
and the second was
 Unable to load a failsafesession
 Unsable to determine failsafe session name.  Possible causes:
 xfconfd isn't running (D-Bus setup problem): environment variable
 $XDG_CONFIG_DIRS is set incorrectly (must include "etc'), or
 xfce4-session is installed incorrectly.

more .xsession-x2go-ourdomain-errors

XSession-x2go: X session started for localuser at Wed Oct 18 09:45:30 EDT 2017

Failed to connect to bus: Connection refused

dbus-update-activation-environment: error: unable to connect to D-Bus: Failed to connect to socket /run/user/xxxx/bus: Connection refused

(imsettings-check:14190): IMSettings-WARNING **: Could not connect: Connection refused

(imsettings-check:14190): GLib-GIO-CRITICAL **: g_dbus_proxy_call_sync_internal: assertion 'G_IS_DBUS_PROXY (proxy)' failed

mate-session[14003]: WARNING: Could not make bus activated clients aware of XDG_CURRENT_DESKTOP=MATE environment variable: Could not connect: Connection refused

mate-session[14003]: WARNING: Could not make bus activated clients aware of DISPLAY=:184 environment variable: Could not connect: Connection refused

mate-session[14003]: WARNING: Could not make bus activated clients aware of MATE_DESKTOP_SESSION_ID=this-is-deprecated environment variable: Could not connect: Connection refused

mate-session[14003]: dconf-WARNING: failed to commit changes to dconf: Could not connect: Connection refused

mate-session[14003]: WARNING: Could not make bus activated clients aware of SESSION_MANAGER=local/unix:@/tmp/.ICE-unix/14003,unix/unix:/tmp/.ICE-unix/14003 environment variable: Could not connect: Connection refused

Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.

mate-session[14003]: Gtk-CRITICAL: gtk_main_quit: assertion 'main_loops != NULL' failed

mate-session[14003]: CRITICAL: dbus_g_proxy_new_for_name: assertion 'connection != NULL' failed

Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.

mate-session[14003]: Gtk-CRITICAL: gtk_main_quit: assertion 'main_loops != NULL' failed

mate-session[14003]: GLib-GObject-CRITICAL: g_object_unref: assertion 'G_IS_OBJECT (object)' failed

mate-session[14003]: WARNING: Could not make bus activated clients aware of GTK_OVERLAY_SCROLLING=0 environment variable: Could not connect: Connection refused

mate-session[14003]: WARNING: keycode1 not existent

mate-session[14003]: WARNING: keycode2 not existent

mate-session[14003]: WARNING: GSIdleMonitor: IDLETIME counter not found

mate-session[14003]: GLib-GObject-CRITICAL: object GSIdleMonitor 0x556fe2443c80 finalized while still in-construction

mate-session[14003]: GLib-GObject-CRITICAL: Custom constructor for class GSIdleMonitor returned NULL (which is invalid). Please use GInitable instead.

mate-session[14003]: CRITICAL: error getting session bus: Failed to connect to socket /run/user/xxxx/bus: Connection refused

mate-session[14003]: WARNING: Unable to register presence with session bus

mate-session[14003]: CRITICAL: dbus_g_proxy_new_for_name: assertion 'connection != NULL' failed

mate-session[14003]: CRITICAL: error getting session bus: Failed to connect to socket /run/user/xxxx/bus: Connection refused