I have done much research and attempted fixes on this issue, mostly involving tweaking the xstartup file. I've tried alternative VNC clients (UltraVNC and TightVNC) from a Windows 7 computer, with the same results for each client.Basically, I get either a blank grey screen with only an arrow cursor, or a failure to connect at all.I also tried a different VNC server (VNC4server) but abandoned that because, although I could connect, I got an error every time on the client window. And Tightvnc seems more widely used and user-supported.I find that, almost regardless of what I put in the ~/.vnc/xstartup file (for example, even if it has just one line (startkde &) it will work if I specify root as the VNC user. But then I'm logged in as root and I need instead to follow standard *nix practice of being logged in as a non-root user. So, the issue does appear to relate to privileges. However, I check for correct ownership and executable flags on files after every time I edit them.I read somewhere that the latest Tightvnc server will not allow KDE desktop to be started if there is already a desktop session running on the host (user logged in), so I start the host machine without anyone logged in. I have configured Tightvnc server as a service.My current xstartup file follows, but like I said, I have already attempted many variants of these lines, commenting out nearly everything, from suggestions gathered on the internet.#!/bin/sh  # Uncomment the following two lines for normal desktop:  unset SESSION_MANAGER  exec /etc/X11/xinit/xinitrc &     # unset DBUS_SESSION_BUS_ADDRESS  [ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup  [ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources  xsetroot -solid grey  vncconfig -iconic &  x-terminal-emulator -geometry 80x24+10+10 -ls -title $VNCDESKTOP Desktop &     # x-window-manager &  exec startkde &  Here is the service file, /lib/systemd/system/tightvncserver.service :[Unit]  Description=TightVNC remote desktop server  After=sshd.service  [Service]  Type=dbus  ExecStart=/usr/bin/vncserver -geometry 1024x768 -depth 24 :1  User=vnc  Type=forking  [Install]  WantedBy=multi-user.target  Here is the log after one reboot of the host followed by one connection attempt:14/03/16 01:37:46 Xvnc version TightVNC-1.3.9  14/03/16 01:37:46 Copyright (C) 2000-2007 TightVNC Group  14/03/16 01:37:46 Copyright (C) 1999 AT&T Laboratories Cambridge  14/03/16 01:37:46 All Rights Reserved.  14/03/16 01:37:46 See http://www.tightvnc.com/ for information on TightVNC  14/03/16 01:37:46 Desktop name 'X' (test:1)  14/03/16 01:37:46 Protocol versions supported: 3.3, 3.7, 3.8, 3.7t, 3.8t  14/03/16 01:37:46 Listening for VNC connections on TCP port 5901  /home/vnc/.vnc/xstartup: 12: /home/vnc/.vnc/xstartup: vncconfig: not found  x-terminal-emulator: Unknown option 'ls'.  x-terminal-emulator: Use --help to get a list of available command line options.  Error: cannot create directory /tmp/ksocket-vncw1nXNU: File exists  startkde: Starting up...  kdeinit4: Aborting. bind() failed: Address already in use  Could not bind to socket '/tmp/ksocket-vncGcyXe4/kdeinit4__1'  14/03/16 01:38:09 Got connection from client 192.168.10.10  14/03/16 01:38:09 Using protocol version 3.8  14/03/16 01:38:14 Full-control authentication passed by 192.168.10.10  14/03/16 01:38:14 Pixel format for client 192.168.10.10:  14/03/16 01:38:14   32 bpp, depth 24, little endian  14/03/16 01:38:14   true colour: max r 255 g 255 b 255, shift r 16 g 8 b 0  14/03/16 01:38:14   no translation needed  14/03/16 01:38:14 Using hextile encoding for client 192.168.10.10  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding 19  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding 18  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding 17  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding 16  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding 10  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding 9  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding 8  14/03/16 01:38:14 Using compression level 6 for client 192.168.10.10  14/03/16 01:38:14 Enabling full-color cursor updates for client 192.168.10.10  14/03/16 01:38:14 Enabling cursor position updates for client 192.168.10.10  14/03/16 01:38:14 Using image quality level 6 for client 192.168.10.10  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding -65530  14/03/16 01:38:14 Enabling LastRect protocol extension for client 192.168.10.10  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding -223  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding -32768  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding -32767  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding -32764  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding -32766  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding -32765  14/03/16 01:38:14 rfbProcessClientNormalMessage: ignoring unknown encoding -1063131698  14/03/16 01:38:43 Client 192.168.10.10 gone  14/03/16 01:38:43 Statistics:  14/03/16 01:38:43   key events received 0, pointer events 260  14/03/16 01:38:43   framebuffer updates 2, rectangles 5, bytes 776789  14/03/16 01:38:43     cursor shape updates 2, bytes 4920  14/03/16 01:38:43     cursor position updates 1, bytes 12  14/03/16 01:38:43     hextile rectangles 2, bytes 771857  14/03/16 01:38:43   raw bytes equivalent 6291480, compression ratio 8.151095  Any ideas?[EDIT, 2014/03/14, 1409 UTC]: I forgot to mention that I had it working error-free with XFCE desktop. But I much prefer KDE, and I wish to get that working if at all possible.[EDIT, 2014/03/14, 2216 UTC]: This is a follow-up to Paul H.'s suggestion, I'm putting it here because the mini-formatting of comments doesn't seem to allow blockquotes and images.Thank you, that got me further. After I give the startkde & command, the client window opens with a sensible-looking desktop that is starting to load and gets this far before closing (note the error message in top left):The log is as follows:14/03/16 21:32:11 Desktop name 'X' (test:1)  14/03/16 21:32:11 Protocol versions supported: 3.3, 3.7, 3.8, 3.7t, 3.8t  14/03/16 21:32:11 Listening for VNC connections on TCP port 5901  QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.  QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.    14/03/16 21:32:37 Got connection from client 192.168.10.10  14/03/16 21:32:37 Using protocol version 3.8  14/03/16 21:32:47 Full-control authentication passed by 192.168.10.10  14/03/16 21:32:47 Pixel format for client 192.168.10.10:  14/03/16 21:32:47   32 bpp, depth 24, little endian  14/03/16 21:32:47   true colour: max r 255 g 255 b 255, shift r 16 g 8 b 0  14/03/16 21:32:47   no translation needed  14/03/16 21:32:47 Using hextile encoding for client 192.168.10.10  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding 19  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding 18  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding 17  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding 16  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding 10  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding 9  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding 8  14/03/16 21:32:47 Using compression level 6 for client 192.168.10.10  14/03/16 21:32:47 Enabling full-color cursor updates for client 192.168.10.10  14/03/16 21:32:47 Enabling cursor position updates for client 192.168.10.10  14/03/16 21:32:47 Using image quality level 6 for client 192.168.10.10  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding -65530  14/03/16 21:32:47 Enabling LastRect protocol extension for client 192.168.10.10  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding -223  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding -32768  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding -32767  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding -32764  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding -32766  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding -32765  14/03/16 21:32:47 rfbProcessClientNormalMessage: ignoring unknown encoding -1063131698  Connecting to deprecated signal QDBusConnectionInterface::serviceOwnerChanged(QString,QString,QString)  QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.  QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.  kbuildsycoca4 running...  kbuildsycoca4(989) KBuildSycoca::checkTimestamps: checking file timestamps  kbuildsycoca4(989) KBuildSycoca::checkTimestamps: timestamps check ok  kbuildsycoca4(989) kdemain: Emitting notifyDatabaseChanged ()  QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.  QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.  Object::connect: No such signal org::freedesktop::UPower::DeviceAdded(QString)  Object::connect: No such signal org::freedesktop::UPower::DeviceRemoved(QString)  QDBusConnection: name 'org.freedesktop.UDisks2' had owner '' but we thought it was ':1.11'  klauncher: Exiting on signal 15  knotify4: Fatal IO error: client killed  kded4: Fatal IO error: client killed  konsole: Fatal IO error: client killed  konsole(902) Konsole::SessionManager::~SessionManager: Konsole SessionManager destroyed with sessions still alive     The first error message, ending with application may misbehave, is supposed to be unimportant, from the bug reports I have seen. The rest, I'm not sure about..
Getting Tightvnc Server Working on Debian 8 (with KDE)
debian;vnc