"Screen on" then nothing at login

[Linux for blind general discussion]

Hello,

each time I boot now my Ubuntu 20.04.3 LTS with Gnome as graphical desktop,
I no longer hear Espeak talking, and the one and only message I can read is
"Scherm aan" what means "Screen on" in English.

How can I trace the source of the problem ? Here is my .xsession-errors, but
are there other useful files to check ? 

Cf. .xsession-errors: 

### 

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/aldo/.Xauthority
dbus-update-activation-environment: setting GTK_MODULES=gail:atk-bridge
dbus-update-activation-environment: setting QT_ACCESSIBILITY=1
dbus-update-activation-environment: setting SHELL=/bin/bash
dbus-update-activation-environment: setting QT_ACCESSIBILITY=1
dbus-update-activation-environment: setting XDG_CONFIG_DIRS=/etc/xdg/xdg-unity:/etc/xdg
dbus-update-activation-environment: setting XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session0
dbus-update-activation-environment: setting GTK_IM_MODULE=ibus
dbus-update-activation-environment: setting GTK2_MODULES=overlay-scrollbar
dbus-update-activation-environment: setting LANGUAGE=nl_BE:nl
dbus-update-activation-environment: setting QT4_IM_MODULE=ibus
dbus-update-activation-environment: setting MANDATORY_PATH=/usr/share/gconf/unity.mandatory.path
dbus-update-activation-environment: setting XMODIFIERS=@im=ibus
dbus-update-activation-environment: setting DESKTOP_SESSION=unity
dbus-update-activation-environment: setting GTK_MODULES=gail:atk-bridge
dbus-update-activation-environment: setting PWD=/home/aldo
dbus-update-activation-environment: setting XDG_SESSION_DESKTOP=unity
dbus-update-activation-environment: setting LOGNAME=aldo
dbus-update-activation-environment: setting QT_QPA_PLATFORMTHEME=appmenu-qt5
dbus-update-activation-environment: setting XDG_SESSION_TYPE=x11
dbus-update-activation-environment: setting GPG_AGENT_INFO=/run/user/1000/gnupg/S.gpg-agent:0:1
dbus-update-activation-environment: setting XAUTHORITY=/home/aldo/.Xauthority
dbus-update-activation-environment: setting XDG_GREETER_DATA_DIR=/var/lib/lightdm-data/aldo
dbus-update-activation-environment: setting LD_PRELOAD=libgtk3-nocsd.so.0
dbus-update-activation-environment: setting GDM_LANG=nl
dbus-update-activation-environment: setting HOME=/home/aldo
dbus-update-activation-environment: setting IM_CONFIG_PHASE=1
dbus-update-activation-environment: setting LANG=nl_BE.UTF-8
dbus-update-activation-environment: setting XDG_CURRENT_DESKTOP=Unity:Unity7:ubuntu
dbus-update-activation-environment: setting XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0
dbus-update-activation-environment: setting GTK_CSD=0
dbus-update-activation-environment: setting CLUTTER_IM_MODULE=ibus
dbus-update-activation-environment: setting XDG_SESSION_CLASS=user
dbus-update-activation-environment: setting DEFAULTS_PATH=/usr/share/gconf/unity.default.path
dbus-update-activation-environment: setting USER=aldo
dbus-update-activation-environment: setting DISPLAY=:0
dbus-update-activation-environment: setting SHLVL=1
dbus-update-activation-environment: setting QT_IM_MODULE=ibus
dbus-update-activation-environment: setting XDG_RUNTIME_DIR=/run/user/1000
dbus-update-activation-environment: setting XDG_DATA_DIRS=/usr/share/unity:/usr/local/share:/usr/share:/var/lib/snapd/desktop:/var/lib/snapd/desktop
dbus-update-activation-environment: setting PATH=/home/aldo/.local/bin:/home/aldo/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
dbus-update-activation-environment: setting GDMSESSION=unity
dbus-update-activation-environment: setting DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
dbus-update-activation-environment: setting _=/usr/bin/dbus-update-activation-environment
Failed to get properties: Unit name gnome-session-manager at .service is neither a valid invocation ID nor unit name.

###

Thanx,

Aldo.