i've been pulling my hair off for 2 weeks now to get vnc4server to work.
after a fresh install with the lastest netinst of Debian 9 (all option to default except printing server and installed gnome) i've run as root (su command) :
apt-get install vnc4server
the installation goes well, but when i run "vncserver" it can't open any instance, i get prompt for a password, but when i enter "vncserver -list" no vnc server are running...
when i try to start it as root logs are :
Warning: nasbiantest:1 is taken because of /tmp/.X11-unix/X1
Remove this file if there is no X server nasbiantest:1
You will require a password to access your desktops.
Password:
Verify:
Would you like to enter a view-only password (y/n)? n
New 'nasbiantest:2 (nathan)' desktop at :2 on machine nasbiantest
Starting applications specified in /etc/X11/Xvnc-session
Log file is /home/nathan/.vnc/nasbiantest:2.log
Use xtigervncviewer -SecurityTypes VncAuth -passwd /home/nathan/.vnc/passwd :2 to connect to the VNC server.
vncserver: Failed command '/etc/X11/Xvnc-session': 256!
=================== tail -15 /home/nathan/.vnc/nasbiantest:2.log ===================
Xvnc TigerVNC 1.7.0 - built Apr 9 2017 14:38:13
Copyright (C) 1999-2016 TigerVNC Team and many others (see README.txt)
See http://www.tigervnc.org for information on TigerVNC.
Underlying X server release 11903000, The X.Org Foundation
Tue Apr 17 00:08:19 2018
vncext: VNC extension running!
vncext: Listening for VNC connections on local interface(s), port 5902
vncext: created VNC server for screen 0
XIO: fatal IO error 11 (Resource temporarily unavailable) on X server ":2"
after 173 requests (173 known processed) with 0 events remaining.
Killing Xtigervnc process ID 1296... which seems to be deadlocked. Using SIGKILL!
====================================================================================
Starting applications specified in /etc/X11/Xvnc-session has failed.
Maybe try something simple first, e.g.,
tigervncserver -xstartup /usr/bin/xterm
When i try to run the "tigervncserver -xstartup /usr/bin/xterm" as root logs are :
Warning: nasbiantest:1 is taken because of /tmp/.X11-unix/X1
Remove this file if there is no X server nasbiantest:1
New 'nasbiantest:2 (nathan)' desktop at :2 on machine nasbiantest
Starting applications specified in /usr/bin/xterm
Log file is /home/nathan/.vnc/nasbiantest:2.log
Use xtigervncviewer -SecurityTypes VncAuth -passwd /home/nathan/.vnc/passwd :2 to connect to the VNC server.
tigervncserver: Can't start '/usr/bin/xterm': No such file or directory!
=================== tail -15 /home/nathan/.vnc/nasbiantest:2.log ===================
XIO: fatal IO error 11 (Resource temporarily unavailable) on X server ":2"
after 173 requests (173 known processed) with 0 events remaining.
Killing Xtigervnc process ID 1296... which seems to be deadlocked. Using SIGKILL!
Xvnc TigerVNC 1.7.0 - built Apr 9 2017 14:38:13
Copyright (C) 1999-2016 TigerVNC Team and many others (see README.txt)
See http://www.tigervnc.org for information on TigerVNC.
Underlying X server release 11903000, The X.Org Foundation
Tue Apr 17 00:08:40 2018
vncext: VNC extension running!
vncext: Listening for VNC connections on local interface(s), port 5902
vncext: created VNC server for screen 0
Can't exec "/usr/bin/xterm": Aucun fichier ou dossier de ce type at /usr/bin/tigervncserver line 877.
====================================================================================
Starting applications specified in /usr/bin/xterm has failed.
Maybe try something simple first, e.g.,
tigervncserver -xstartup /usr/bin/xterm
and when i try to run "vncserver :4" as user logs are :
Warning: nasbiantest:1 is taken because of /tmp/.X11-unix/X1
Remove this file if there is no X server nasbiantest:1
New 'nasbiantest:2 (nathan)' desktop at :2 on machine nasbiantest
Starting applications specified in /usr/bin/xterm
Log file is /home/nathan/.vnc/nasbiantest:2.log
Use xtigervncviewer -SecurityTypes VncAuth -passwd /home/nathan/.vnc/passwd :2 to connect to the VNC server.
tigervncserver: Can't start '/usr/bin/xterm': No such file or directory!
=================== tail -15 /home/nathan/.vnc/nasbiantest:2.log ===================
XIO: fatal IO error 11 (Resource temporarily unavailable) on X server ":2"
after 173 requests (173 known processed) with 0 events remaining.
Killing Xtigervnc process ID 1296... which seems to be deadlocked. Using SIGKILL!
Xvnc TigerVNC 1.7.0 - built Apr 9 2017 14:38:13
Copyright (C) 1999-2016 TigerVNC Team and many others (see README.txt)
See http://www.tigervnc.org for information on TigerVNC.
Underlying X server release 11903000, The X.Org Foundation
Tue Apr 17 00:08:40 2018
vncext: VNC extension running!
vncext: Listening for VNC connections on local interface(s), port 5902
vncext: created VNC server for screen 0
Can't exec "/usr/bin/xterm": Aucun fichier ou dossier de ce type at /usr/bin/tigervncserver line 877.
====================================================================================
Starting applications specified in /usr/bin/xterm has failed.
Maybe try something simple first, e.g.,
tigervncserver -xstartup /usr/bin/xterm
i've try deleting "/tmp/.X11-unix/X1" with no success
if anyone has any idea i'm seeking for somes

Thank in advance for anyone who had the strenth to read until here and all the others