When using the vglrun script to run a specific application under the provisioning of VirtualGL, the following warning message is issued in the terminal where the program is launched:

ERROR: ld.so: object ' usr/NX/scripts/vgl//usr/NX/scripts/vgl ' from LD_PRELOAD cannot be preloaded (cannot open shared object file).

This happens when both the vglrun script and the 'EnableVirtualGLSupport 1' key are enabled because in this case the vglrun script doesn't cleanup the LD_PRELOAD path properly.

As a workaround enable VirtualGL in the session by using one of these methods (not both!):
1) set 'EnableVirtualGLSupport 1' in node.cfg (that is basically the same as executing command 'nxserver --virtualgl yes') or:
2) set 'EnableVirtualGLSupport 0' in node.cfg  and add vglrun to the desktop command (DefaultDesktopCommand key in node.cfg). See here for some examples: https://kb.nomachine.com/AR05P00982