I have documented how I resolved this issue on my blog: http://brtknr.com/2017/03/15/permission-issues-with-xpra-on-ubuntu-16-04-when-tunnelling-through-SSH/
Turns out that the version of xpra (0.15.x) provided with Ubuntu 16.04 is not supported anymore and updating to 2.0.x resolved the issue. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xserver-xorg-video-dummy in Ubuntu. https://bugs.launchpad.net/bugs/1589447 Title: Xdummy cannot be used in Xenial Status in xserver-xorg-video-dummy package in Ubuntu: Confirmed Bug description: Xdummy is used by several systems for remote display, such as xpra (http://xpra.org/). Unfortunately, since Xenial, it is completely impossible to use Xdummy for anything like that, because of the way in which permissions are set up for running X servers. This results in a serious compromise on the possibility of running remote displays systems on ubuntu. In fact, the latter can only rely on Xvfb with a less than optimal experience. Most important, Trying to run Xdummy from a console session results in /usr/lib/xorg/Xorg.wrap: Only console users are allowed to run the X server It should be possible to start Xdummy from an ssh session. Xdummy is a 'dummy' display driver. It does not touch real hardware. There is no need to prevent users who are not on the console from starting it. In fact, it is not clear what is the purpose of taking the effort of packaging and shipping Xdummy at all, if it cannot be used for the tasks it is intended for. See also: http://xpra.org/trac/ticket/1220 The Xpra developer, whose availability to help is always excellent, explicitly states that: - it is not possible to use xdummy with almost all Ubuntu releases [in fact the problem is Xenial. Before xenial, xdummy required some tweaks, but worked] - xpra needs to be compiled with the --without-Xdummy on Ubuntu because of this - There is nothing that can be done in xpra, because this is an OS permission problem ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: xserver-xorg-video-dummy 1:0.3.7-1build5 ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8 Uname: Linux 4.4.0-22-generic x86_64 ApportVersion: 2.20.1-0ubuntu2.1 Architecture: amd64 CurrentDesktop: KDE Date: Mon Jun 6 11:54:50 2016 EcryptfsInUse: Yes InstallationDate: Installed on 2013-12-12 (906 days ago) InstallationMedia: Kubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1) SourcePackage: xserver-xorg-video-dummy UpgradeStatus: Upgraded to xenial on 2016-04-21 (45 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-dummy/+bug/1589447/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp