VNC connection results in black screen with mouse cursor.

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Environment

SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server 12
Remote Access (VNC) enabled in YaST

Situation

After enabling Remote Access (VNC) in YaST and attempting to connect to the server from a VNC client, a black screen is displayed with a moving mouse cursor. No login screen (gdm) is ever displayed.

Resolution

As the root user edit this file:
/etc/gdm/custom.conf

Locate [xdmcp] and just below it add this line:
Enable=true

Save the file and restart xdm:
systemctl restart xdm

Cause

GDM must be configured to allow xdmcp for remote access. This is normally enabled by default, but in some cases the entry had to be made in the /etc/gdm/custom.conf file for it to take effect.

Additional Information

As a step in testing the issue the "DISPLAYMANGER=" setting was switched to "xdm" rather than "gdm" in /etc/sysconfig/displaymanager and xdm restarted. The xdm displaymanager displayed perfectly when the VNC connection was established.

Disclaimer

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