En principio, según el tutorial de Ubuntu está todo bien (a falta de probar el 
paso de ubuntu.deskop).
No se si esto puede dar alguna pista?


Aquí dijimos que no había nada grave /var/log/lightdm/lightdm.log:

[+0.00s] DEBUG: Loading configuration dirs from /usr/share/lightdm/lightdm.conf>
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/01>
[+0.00s] DEBUG: Loading configuration dirs from /usr/local/share/lightdm/lightd>
[+0.00s] DEBUG: Loading configuration dirs from /etc/xdg/lightdm/lightdm.conf.d
[+0.00s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf.d/lightdm->
[+0.00s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
[+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: Using cross-namespace EXTERNAL authentication (this will deadlo>
[+0.00s] DEBUG: _g_io_module_get_default: Found default implementation local (G>
[+0.00s] DEBUG: Monitoring logind for seats
[+0.00s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.00s] DEBUG: Stopping Plymouth, no displays replace it
[+0.00s] DEBUG: Quitting Plymouth
[+0.03s] WARNING: Could not enumerate user data directory /var/lib/lightdm/data>
[+29.72s] DEBUG: Seat seat0 changes active session to 1
[+129.06s] DEBUG: Seat seat0 changes active session to
[+133.28s] DEBUG: Seat seat0 changes active session to 3
 


Estas líneas se me pasaron por alto /var/log/Xorg.0.log:

[   139.663] (WW) The directory "/usr/share/fonts/X11/cyrillic" does not exist.
[   139.745] (EE) open /dev/dri/card0: No such file or directory
[   139.745] (WW) Falling back to old probe method for modesetting
[   139.745] (EE) open /dev/dri/card0: No such file or directory
[   139.746] (EE) Unable to find a valid framebuffer device
[   139.746] (WW) Falling back to old probe method for fbdev
[   139.746] (EE) open /dev/fb0: No such file or directory
[   139.746] (EE) Screen 0 deleted because of no matching config section.
[   139.746] (EE) Screen 0 deleted because of no matching config section.
[   139.746] (EE) Screen 0 deleted because of no matching config section.
[   139.767] (WW) VESA(0): Unable to estimate virtual size



Y este se me quedó a revisar ~/.xsession-errors:

Xsession: X session started for a at...
dbus-update-activation-environment: setting 
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
dbus-update-activation-environment: setting DISPLAY=:0
dbus-update-activation-environment: setting XAUTHORITY=/home/user/.Xauthority
localuser:a being added to access control list
dbus-update-activation-environment: setting 
XDG_DATA_DIRS=/usr/share/xfce4:/usr/local/share/:/usr/share/
dbus-update-activation-environment: setting GTK_MODULES=gail:atk-bridge
dbus-update-activation-environment: setting QT_ACCESSIBILITY=1
dbus-update-activation-environment: setting USER=user
dbus-update-activation-environment: setting XDG_SESSION_TYPE=x11
dbus-update-activation-environment: setting SHLVL=0
dbus-update-activation-environment: setting HOME=/home/user
dbus-update-activation-environment: setting DESKTOP_SESSION=Default Xsession
dbus-update-activation-environment: setting GTK_MODULES=gail:atk-bridge
dbus-update-activation-environment: setting SYSTEMD_EXEC_PID=802
dbus-update-activation-environment: setting 
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
dbus-update-activation-environment: setting LOGNAME=user
dbus-update-activation-environment: setting JOURNAL_STREAM=8:20102
dbus-update-activation-environment: setting 
MEMORY_PRESSURE_WATCH=/sys/fs/cgroup/system.slice/lxdm.service/memory.pressure
dbus-update-activation-environment: setting XDG_SESSION_CLASS=user
dbus-update-activation-environment: setting 
PATH=/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
dbus-update-activation-environment: setting 
INVOCATION_ID=bb10a96f06984beab99e037003b8dcee
dbus-update-activation-environment: setting XDG_RUNTIME_DIR=/run/user/1000
dbus-update-activation-environment: setting DISPLAY=:0
dbus-update-activation-environment: setting LANG=es_ES.UTF-8
dbus-update-activation-environment: setting XAUTHORITY=/home/user/.Xauthority
dbus-update-activation-environment: setting SHELL=/bin/bash
dbus-update-activation-environment: setting QT_ACCESSIBILITY=1
dbus-update-activation-environment: setting 
GPG_AGENT_INFO=/run/user/1000/gnupg/S.gpg-agent:0:1
dbus-update-activation-environment: setting PWD=/home/user
dbus-update-activation-environment: setting 
XDG_DATA_DIRS=/usr/share/xfce4:/usr/local/share/:/usr/share/
dbus-update-activation-environment: setting 
MEMORY_PRESSURE_WRITE=c29tZSAyMDAwMDAgMjAwMDAwMAA=
/usr/bin/x-session-manager: X server already running on display :0
/usr/bin/iceauth:  creating new authority file /run/user/1000/ICEauthority
xfce4-session-Message: 03:19:07.619: SSH authentication agent is already running
gpg-agent: ya hay un agente gpg ejecutándose - no se inicia otro

(xfwm4:2721): xfwm4-WARNING **: 03:19:07.748: Unsupported GL renderer (llvmpipe 
(LLVM 15.0.7, 256 bits)).

** (xiccd:2789): WARNING **: 03:19:08.040: EDID is empty

** (light-locker:2799): ERROR **: 03:19:08.077: Environment variable 
XDG_SESSION_PATH not set. Is LightDM running?

** (xiccd:2789): CRITICAL **: 03:19:08.130: Gamma size is 0 at output 
xrandr-default
Falla: No existe tal entidad

(wrapper-2.0:2773): Gtk-WARNING **: 03:19:08.570: Negative content width -4 
(allocation 16, extents 10x10) while allocating gadget (node button, owner 
PlacesButton)

(nm-applet:2793): Gdk-CRITICAL **: 03:19:08.601: 
gdk_window_thaw_toplevel_updates: assertion 
'window->update_and_descendants_freeze_count > 0' failed

(xfce4-power-manager:2800): xfce4-power-manager-WARNING **: 03:19:08.799: could 
not map keysym 1008ffa8 to keycode


** (xfce4-power-manager:2800): WARNING **: 03:19:08.827: No outputs have 
backlight property

(xfce4-power-manager:2800): xfce4-power-manager-WARNING **: 03:19:08.830: 
Failed to get keyboard max brightness level : 
GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: El objeto no ex>
weather-Message: 03:19:08.843: obteniendo https://api.met...

** (xiccd:2789): WARNING **: 03:20:54.300: Exiting

Responder a