Failed to acquire the VirtualBox COM object on Ubuntu 14.04 LTS
I encountered this situation after a power loss and reboot of my host system.
Overview
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
).
Options
To solve a corrupted VirtualBox.xml
do one of the following, in order of preference:
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 onVirtualBox.xml
, and choose Revert to previous version... more detailsRestore 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
- Ensure VirtualBox Manager is not running.
- Navigate to
~/.config/VirtualBox/
- Rename
~/.config/VirtualBox/VirtualBox.xml
to something like~/.config/VirtualBox/VirtualBox.xml-original
- Rename the backup
~/.config/VirtualBox/VirtualBox.xml-prev
to~/.config/VirtualBox/VirtualBox.xml
- Start VirtualBox Manager. This is a copy of the state of the last VirtualBox Manager startup, and hopefully resolves your situation.
Remove the file. Always Backup first, including
VirtualBox VMs
. This is a last resort.Steps to remove the file
- Backup
- Navigate to
~/.config/VirtualBox/
- Delete/rename the
VirtualBox.xml
file. - 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
Notes:
- 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.
- To past a path in the location bar of
- Before upgrading: It is prudent to
shutdown
each virtual machine (in lieu of asuspended\snapshot
state). - Before upgrading: It is also important to
eject/unmount
anyVBoxGuestAdditions.iso
in CD drive. Then, new version can be inserted and installed after upgrade.
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.