uses XML for both the machine settings files and the global configuration file, VirtualBox.xml.

All XML files are versioned. When a new settings file is created, for example because a new virtual machine is created, automatically uses the settings format of the current version. These files may not be readable if you downgrade to an earlier version of . However, when encounters a settings file from an earlier version, such as after upgrading , it attempts to preserve the settings format as much as possible. It will only silently upgrade the settings format if the current settings cannot be expressed in the old format, for example because you enabled a feature that was not present in an earlier version of .

In such cases, backs up the old settings file in the virtual machine's configuration directory. If you need to go back to the earlier version of , then you will need to manually copy these backup files back.

We intentionally do not document the specifications of the XML files, as we must reserve the right to modify them in the future. We therefore strongly suggest that you do not edit these files manually. provides complete access to its configuration data through its the VBoxManage command line tool, see VBoxManage and its API, see .