I had VirtualBox 4.3 installed and uninstalled it to have VirtualBox 5.1... big mistake, ever since I keep getting errors, or being unable to install any other version. Already used Synaptic, and

sudo apt-get purge virtualbox

following a suggestion, used the command

sudo apt-get remove virtualbox
apt-get autoremove

which seemed to get rid of some VB dependencies and allowed me to install VB again, but I get this error when I try to start it:

Failed to acquire the VirtualBox COM object. 
The application will now terminate. 
Failed to acquire the VirtualBox COM object. 
The application will now terminate. 
Document is empty.   
Location: '/home/user/.config/VirtualBox/VirtualBox.xml', line 1 (0), column 1.

(nsresult VirtualBox::init()).

Result Code: NS_ERROR_FAILURE (0x80004005) 
Component: VirtualBoxWrap
Interface: IVirtualBox {0169423f-46b4-cde9-91af-1e9d5b6cd945} Callee:
IVirtualBoxClient {d2937a8e-cb8d-4382-90ba-b7da78a74573}

What should I do?

  • You must COMPLETELY uninstall ALL of vbox before attempting to install another version. The method of uninstalling depends entirely upon how you originally installed that version - apt/synaptic can remove ONLY packages they installed.
    – user535733
    May 26, 2017 at 4:00

3 Answers 3


I encountered this situation after a power loss and reboot of my host system.


VirtualBox stores its global configuration in ~/.config/VirtualBox/VirtualBox.xml, (if you've upgraded from early versions it may be in ~/.VirtualBox/VirtualBox.xml). The file includes global configuration options and the list of registered virtual machines with pointers to their XML settings files (for each machine under ~/VirtualBox VMs).


To solve a corrupted VirtualBox.xml do one of the following, in order of preference:

  1. Restore a backup. Ubuntu comes with Backups (Déjà Dup) installed by default. If you're using it, you can easily restore the file by navigating to ~/.config/VirtualBox/, right-clicking on VirtualBox.xml, and choose Revert to previous version... more details

  2. Restore a copy. Each time VirtualBox Manager starts up, it creates a backup copy of ~/.config/VirtualBox/VirtualBox.xml (called ~/.config/VirtualBox/VirtualBox.xml-prev). The drawback is this file will/may only be useful if you haven't started VirtualBox Manager.

    Steps to restore a copy

    1. Ensure VirtualBox Manager is not running.
    2. Navigate to ~/.config/VirtualBox/
    3. Rename ~/.config/VirtualBox/VirtualBox.xml to something like ~/.config/VirtualBox/VirtualBox.xml-original
    4. Rename the backup ~/.config/VirtualBox/VirtualBox.xml-prev to ~/.config/VirtualBox/VirtualBox.xml
    5. Start VirtualBox Manager. This is a copy of the state of the last VirtualBox Manager startup, and hopefully resolves your situation.
  3. Remove the file. Always Backup first, including VirtualBox VMs. This is a last resort.

    Steps to remove the file

    1. Backup
    2. Navigate to ~/.config/VirtualBox/
    3. Delete/rename the VirtualBox.xml file.
    4. Start VirtualBox Manager. This will recreate a file during startup.
      The result of removing the file will likely be a loss of some/all of your machines in the list. Any missing machines might be able to be restored by re-registering .vbox files and {snapshot}.vdi files stored by default in the ~/VirtualBox VMs folder. Full details of how to recover this condition are beyond the scope of this question. Always


  • The tilde (~) is a shortcut representation for the $HOME environment variable. It can be cut-and-paste into a GUI program like Gnome Files (Nautilus) (which supports freedesktop.org conventions), or in a terminal.
    • To past a path in the location bar of Gnome Files (Nautilus), press CTRL-L. Then type or paste a path.
  • Before upgrading: It is prudent to shutdown each virtual machine (in lieu of a suspended\snapshot state).
  • Before upgrading: It is also important to eject/unmount any VBoxGuestAdditions.iso in CD drive. Then, new version can be inserted and installed after upgrade.
  • 1
    Mine /home/myuser/.config/VirtualBox/VirtualBox.xml was completely empty x) , so I've copied contents from /home/myuser/.config/VirtualBox/VirtualBox.xml-prev into it as you've suggested and it worked! :)
    – jave.web
    Jul 31, 2020 at 13:00

I faced the similar issue, removing the xml file resolved this for me. So for you please do

rm /home/user/.config/VirtualBox/VirtualBox.xml

and start virtualbox again.

  • 2
    I'd suggest moving instead of removing. ;-) Always better practice to have a backup in case things don't go as expected. Try: mv /home/user/.config/VirtualBox/VirtualBox.xml ~/ --> which will move VirtualBox.xml to your $HOME folder. Alternatively, use a GUI File Manager such as Gnome Files (originally Nautilus) to remove to Trash or move somewhere. Sep 4, 2020 at 0:04

All of this was very helpful. Thanks very much.

I tried using the "prev" version, which didn't work. Then moved VirtualBox.xml to a backup and started up VirtualBox. That showed a new, empty system with no VMs. I started up each of the VM's by right-clicking and "open with Virtualbox". They started up as before and are now available in the VM list when I open Virtualbox.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.