VirtualBox & unknown version of X Window system

Updated: September 3, 2016

Here's my story. As it happens, I was testing Fedora 23 in VirtualBox one day, and as a very first step to enjoying myself, I decided to install the Guest Additions. However, after a few brief, tense moments, VirtualBox told me that it had detected an unknown version of the X Window System installed and was not installing X Window System drivers.

A quick search on the VirtualBox ticketary lists this as a five-month old bug for VirtualBox 4.3, even though I was running 5.0.6, and it mentions upgrading to a newer version of the virtualization software as a fix, which I could not do at this point. So what now?

Let's hack ourselves a fix, shall we?

Now, we have one version of VirtualBox installed, and then we want Fedora to run on top of it without any big problems. But the current set of drivers is not good enough, and yet we cannot upgrade, or we are not allowed to upgrade. In this case, it may seem as if we're stuck. But we're not really.

Installing the Window System drivers
Warning: unknown version of the X Window System installed. Not installing X Window System drivers.[  OK  ]

What we essentially need to do is install a newer version of Guest Additions, as they contain the right drivers for Fedora. You may think mixing different versions of VirtualBox and drivers may not be a good idea, and in essence, you're right. But if this is the only option you have, or rather, the first one you want to explore before moving forward, you might as well follow this tutorial to its end. Indeed, the recommended fix is completely non-intrusive, and it does not require any software installations on the host.

What we want to do is download a newer set of Guest Additions than the one we have. In my case, VirtualBox was at version 5.0.6, whereas the site listed version 5.0.16 as the most current one, at the time this article was compiled.

Download the newer ISO file and then mount it in the guest operating system. You can do this through the settings menu, so the ISO file is presented as a virtual CD drive inside the guest, or alternatively, inside the guest, mount the file as a loopback device.

Newer ISO

mount -o loop <iso file> /mountpoint

After that, the installation procedure is just like my Guest Additions guide.

Verifying archive integrity... All good.
Uncompressing VirtualBox 5.0.16 Guest Additions for Linux............
VirtualBox Guest Additions installer
Removing installed version 5.0.6 of VirtualBox Guest Additions...
Removing existing VirtualBox non-DKMS kernel modules[  OK  ]
Copying additional installer modules ...
Installing additional modules ...
Removing existing VirtualBox non-DKMS kernel modules[  OK  ]
Building the VirtualBox Guest Additions kernel modules
Building the main Guest Additions module[  OK  ]
Building the shared folder support module[  OK  ]
Building the OpenGL support module[  OK  ]
Doing non-kernel setup of the Guest Additions[  OK  ]
You should restart your guest to make sure the new modules are actually used

Installing the Window System drivers
Installing X.Org Server 1.18 modules[  OK  ]
Setting up the Window System to use the Guest Additions[  OK  ]
You may need to restart the the Window System (or just restart the guest system) to enable the Guest Additions.

Installing graphics libraries and desktop services
components[  OK  ].

It is implied in all the homework reading you need to do, but this tutorial assumes you are somewhat comfortable with the command line, you have installed the necessary tools for compilation - make, gcc, kernel source, kernel headers - and you are using a Linux guest operating system. All good.


This guide presents a fairly innocent workaround to the problem of having a guest operating system that is perhaps too modern for your version of VirtualBox. If you cannot upgrade the software, then you can try installing Guest Additions from an ISO image that is newer than your VirtualBox edition. This should work fairly well and without any great side effects. I would not recommend this in production, but then, neither VirtualBox nor Fedora are the staple food of the corporate business world.

Anyhow, if this fix does not work, you can then try the full upgrade. As it stands, it requires no special hacking, and you can complete everything in one session, with a single reboot of the guest operating system, or if you're lazy, an X Window restart. Worth trying, and the lessons learned here should apply to a whole bunch of tiny bugs and issues that may sometimes crop in between VirtualBox releases and Linux distro milestones. Enjoy.


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