ClipConstructX11: disabling shared clipboard
tldr: If you need shared clipboard don’t run VMs in headless-mode. During the last days at work I notices my shared clipboard in Virtualbox was not working. After checking everything I found this in the logs of the affected VM: ClipConstructX11: X11 DISPLAY variable not set -- disabling shared clipboard Why is there no DISPLAY set? Well, the VM was started in headless-mode, everything makes sense now.