Black Screen: VNC on Debian 8

[GuiltySpark]

I don't think the startup file is the problem. I have found something that looks similar to what you're going through read through and see what you can do: https://stackoverflow.com/questions/19639221/vnc-black-screen-with-a-x-cursor-on-red-hat-enterprise-linux-server-release-5-3

[baker7]

I will try this and see if it works: I have to go to the office in the AM to do some work, so I can test it from a true remote location. I have already changed the mode of the xstartup file to 755 - I have read most of the good info you gave me, and hopefully, will be able to get it to work.

Thanks for hanging with me during this exasperating problem

Brian

[baker7]

(03-27-2016, 09:59 PM)baker7 Wrote:  I will try this and see if it works:  I have to go to the office in the AM to do some work, so I can test it from a true remote location.  I have already changed the mode of the xstartup file to 755 - I have read most of the good info you gave me, and hopefully, will be able to get it to work.

Thanks for hanging with me during this exasperating problem

Brian

Guiltyspark:

I will look at this tomorrow while I am working on the console. I have been looking at this stuff and wondering if I am going crazy: IF I get this running again, I am gonna post it to my Blog, to my webpage, and save a copy to my files so I can know how to fix this, as there are a lot of problems with this, and it can get confusing.

Brian

[baker7]

VNC Support sent me this:


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VNC Server in Virtual Mode appears to hang or you see a grey screen because a desktop environment cannot be loaded



The default desktop environments used by RHEL/CentOS 7+, Ubuntu 13.04+ and Fedora 19+ (Unity and Gnome Shell) do not work under VNC Server in Virtual Mode because they require capabilities that are not available in the bundled X server (Xvnc). This is also true of the "2D" or "fallback" modes, which used to work in previous releases of these distributions. To use VNC Server in Virtual Mode on these systems, we recommend installing and using an alternative desktop environment.

Also, because VNC Server works by detecting parts of the screen which have changed and sending updates to VNC Viewer, you will generally get a better experience when using a desktop environment that does not cause unnecessary changes to the screen (for example, through fading, transparency or fullscreen effects). This is particularly important over a slow network connection.

Desktop environments which are known to work well under VNC Server in Virtual Mode are as follows:



Desktop Environment Package name for Debian systems Package group for Fedora systems
Xfce xfce4 @xfce-desktop
LXDE lxde @lxde-desktop
KDE Plasma Desktop kde-plasma-desktop @kde-desktop


In addition, older distributions which use Gnome 2 are also known to work well (for example CentOS 5/6).

Each of the above should be easily installable on most Linux systems using the normal application installer. You can also do this from the command line using the package names mentioned in the table for Debian or Fedora-based systems - for other distributions you may need to search for the exact package name. There are also distributions which use these desktops by default (or example the Xubuntu, or Kubuntu "flavours" of Ubuntu).

If the desktop environment you've installed is not the default (for example, you've installed LXDE on a regular Ubuntu system), you will need to modify the xstartup script used by VNC Server to start your chosen desktop environment. Each desktop session should have a corresponding .desktop file in /usr/share/xsessions, which contains the command used to start the environment. You can use the following command to list the startup commands for all the available sessions installed on the system:

grep Exec= /usr/share/xsessions/*.desktop

Next, use a text editor to replace the existing xstartup script with the following template:

#!/bin/sh
DESKTOP_SESSION=name-of-desktop-file
export DESKTOP_SESSION
exec-command-from-desktop-file
vncserver-virtual -kill $DISPLAY

This should be saved to ~/.vnc/xstartup, or /etc/vnc/xstartup.custom for all users on the system, and made executable using chmod +x.

Example for Xfce:

#!/bin/sh
DESKTOP_SESSION=xfce
export DESKTOP_SESSION
startxfce4
vncserver-virtual -kill $DISPLAY

Example for LXDE:

#!/bin/sh
DESKTOP_SESSION=LXDE
export DESKTOP_SESSION
startlxde
vncserver-virtual -kill $DISPLAY

There is also a known issue with the RENDER extension in current versions of Xvnc that causes problems with Xfce, resulting in the desktop failing to start. This can be solved by disabling the RENDER extension; to do this, create /etc/vnc/config.custom (if it does not already exist) and add the command:

-extension RENDER


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---

From VNC support:
I'm afraid I can't access the information at the site you linked to as it's blocked due to malware.

Going from your description, the reason for the issue you face is that VNC Server doesn't work well with version 3 of Gnome (including the Cinnamon desktop environment) in Virtual mode. For this circumstance, I'd recommend using an alternative desktop such as XFCE or KDE as per the following article:

https://support.realvnc.com/knowledgebase/article/View/345/5/vnc-server-in-virtual-mode-appears-to-hang-or-you-see-a-grey-screen-because-a-desktop-environment-cannot-be-loaded

In addition to the desktops listed, I've successfully used the MATE desktop in Virtual mode.

Regards,
Ally
RealVNC Product Support

Ticket Details

--------------------------------------------------------------------------------
Ticket ID: DZK-784-44461
Status: On Hold
------------------------------------------------------------------------------------------------

(04-18-2016, 10:50 AM)baker7 Wrote:  VNC Support sent me this:


-------------------------------------------------------------------------------------------------------------------------------------
VNC Server in Virtual Mode appears to hang or you see a grey screen because a desktop environment cannot be loaded



The default desktop environments used by RHEL/CentOS 7+, Ubuntu 13.04+ and Fedora 19+ (Unity and Gnome Shell) do not work under VNC Server in Virtual Mode because they require capabilities that are not available in the bundled X server (Xvnc). This is also true of the "2D" or "fallback" modes, which used to work in previous releases of these distributions. To use VNC Server in Virtual Mode on these systems, we recommend installing and using an alternative desktop environment.

Also, because VNC Server works by detecting parts of the screen which have changed and sending updates to VNC Viewer, you will generally get a better experience when using a desktop environment that does not cause unnecessary changes to the screen (for example, through fading, transparency or fullscreen effects). This is particularly important over a slow network connection.

Desktop environments which are known to work well under VNC Server in Virtual Mode are as follows:



Desktop Environment Package name for Debian systems Package group for Fedora systems
Xfce xfce4 @xfce-desktop
LXDE lxde @lxde-desktop
KDE Plasma Desktop  kde-plasma-desktop @kde-desktop


In addition, older distributions which use Gnome 2 are also known to work well (for example CentOS 5/6).

Each of the above should be easily installable on most Linux systems using the normal application installer. You can also do this from the command line using the package names mentioned in the table for Debian or Fedora-based systems - for other distributions you may need to search for the exact package name. There are also distributions which use these desktops by default (or example the Xubuntu, or Kubuntu "flavours" of Ubuntu).

If the desktop environment you've installed is not the default (for example, you've installed LXDE on a regular Ubuntu system), you will need to modify the xstartup script used by VNC Server to start your chosen desktop environment. Each desktop session should have a corresponding .desktop file in /usr/share/xsessions, which contains the command used to start the environment. You can use the following command to list the startup commands for all the available sessions installed on the system:

grep Exec= /usr/share/xsessions/*.desktop

Next, use a text editor to replace the existing xstartup script with the following template:

#!/bin/sh
DESKTOP_SESSION=name-of-desktop-file
export DESKTOP_SESSION
exec-command-from-desktop-file
vncserver-virtual -kill $DISPLAY

This should be saved to ~/.vnc/xstartup, or /etc/vnc/xstartup.custom for all users on the system, and made executable using chmod +x.

Example for Xfce:

#!/bin/sh
DESKTOP_SESSION=xfce
export DESKTOP_SESSION
startxfce4
vncserver-virtual -kill $DISPLAY

Example for LXDE:

#!/bin/sh
DESKTOP_SESSION=LXDE
export DESKTOP_SESSION
startlxde
vncserver-virtual -kill $DISPLAY

There is also a known issue with the RENDER extension in current versions of Xvnc that causes problems with Xfce, resulting in the desktop failing to start. This can be solved by disabling the RENDER extension; to do this, create /etc/vnc/config.custom (if it does not already exist) and add the command:

-extension RENDER


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[GuiltySpark]

So basically it does not display with a Gnome interface but the likes of KDE, LXDE and XFCE run fine. Must be an issue with resources within the program itself as those desktops are lightweight whereas Gnome is a little heavier.

Still glad you were able to get things sorted

Does surprise me though, that VNC doesn't sit well with Gnome????

[baker7]

Guiltyspark:

I would like to be able to have a desktop that DOES work with VNC4server, but they are so OLD that I am worried that I will be missing some functionality due to the incompatibilities with Gnome3. They say that Gnome2 works with vnc4server, but gnome2 is not available anymore, so I am using mate. I have tested all of the desktops the RealVNC Support people told me work with Vnc4server.

It would help if I could download compatible desktop environments - I tried to compile one, and she died because I was following what I thought was inconsistent directions - I have only compiled like 2 things in my life, so I was a little out of my league.

Is there another VNC-Like server application that does the same thing, that is compatible with cinnamon??

Brian

[GuiltySpark]

I believe TigerVNC works on Cinnamon but have never tried it: https://tigervnc.org/

You could give it a try and see if that works just remember to change you startup file to work with Cinnamon.

[baker7]

Guiltyspark:

Checking to see if tigervnc has a server component: If it does and this works, I would rather run Cinnamon or Unity and add a couple lines to sources.list, so I get more selections

Thanks for the help so far

Brian

[baker7]

Installed tigervnc and ran THIS:

Code:

#!/bin/sh

# Uncomment the following two lines for normal desktop:
unset SESSION_MANAGER
unset DBUS_SESSION_BUS_ADDRESS
#sh /etc/X11/xinit/xinitrc

xrdb $HOME/.Xresources
#xsetroot -solid grey
x-terminal-emulator -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
#x-window-manager &
# Fix to make GNOME work
export XKL_XMODMAP_DISABLE=1
#/etc/X11/Xsession
#exec /usr/bin/gnome-session --session=gnome-classic &
gnome-session --session=gnome-fallback &

and got THIS:

"Oh No, something went wrong"
A LOGOUT Button

and a Grey checked Screen

I wish there was a VNC serevr that was updated to deal with the NEWER desktops: all of these I have tried are REALLY old

Brian

[GuiltySpark]

To setup Desktop environment it should be:

Quote:nano ~/.vnc/xstartup

And the xstartup should be something as simple as:

Quote:#!/bin/sh
#
exec /usr/bin/cinnamon-session

Your current one is still Gnome orientated and not Cinnamon.