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Searching in: Trouble Reports
ID: TR08Q09375
Added on: 2019-08-05
Last update: 2020-04-24
Solved in: 6.8.1
Platform: All Linux Platforms
Product: NoMachine Server
Severity: Minor
Status: Closed
VirtualGL errors on RHEL 8 when GDM is used

On RHEL 8, enabling NoMachine VirtualGL support when the GDM display manager is in use arises the following error in /var/log/messages:

No protocol specified

[VGL] ERROR: Could not open display :0.

This problem is solved in the newer version of VirtualGL (v. 2.6.2) which will be included in the next release of NoMachine packages (the current packages v. 6.7 provide VirtualGL-2.5.2).


As a temporary workaround, it's possible to use for example LightDM as display manager. This display manager is not present in the official RHEL 8 repositories but can be installed manually by downloading it from the Fedora 28 repositories.

Retrieve and install these packages:



Then run the following commands:

 systemctl stop gdm
 systemctl disable gdm
 systemctl enable lightdm
 systemctl start lightdm

Configure the system for VirtualGL:

 /etc/NX/nxserver --virtualgl-install

Editing the DefaultDesktopCommand key in /usr/NX/etc/node.cfg to start the GNOME desktop using the following command:

DefaultDesktopCommand  "/etc/gdm/Xsession 'env __GLX_VENDOR_LIBRARY_NAME=nvidia GNOME_SHELL_SESSION_MODE=classic XDG_SESSION_TYPE=x11 /usr/NX/scripts/vgl/vglrun gnome-session --session=gnome-classic --disable-acceleration-check' "