VirtualBox Knowledge Base

The VirtualBox knowledge base is a database of common questions along with their answers and should be consulted every time you run into a problem that is not described in the product manual. The knowledge base is updated on a daily basis and it is best to use the search feature of the site to find suitable information.

• Linux hosts: If you get permission problems directly after an installation, make sure that your user account is listed in the vboxusers group. The installation takes care creating that group, but you will need to manually add all users to it that should be allowed to run VirtualBox. As root, for each such user, run "usermod -G vboxusers -a <userid>". If any of the affected users are currently logged in, they need to log out for the changes to take effect. In case any user already attempted to start VirtualBox before logging out (which launches the VBoxSVC service process with incorrect permissions), that user additionally needs to run "VirtualBox shutdown" from the command line to terminate the service. This solves the permission problems. (Alternatively, a reboot will help as well.)

• Linux hosts: When the kernel module doesn't load, i.e. you get an "Error inserting vboxdrv: Invalid argument", check (as root) the output of the "dmesg" command. In 90% of all cases, this is a problem with Linux 2.6.19 and higher, and the message will be: "NMI watchdog active -- refused to load the kernel module! Please disable the NMI watchdog by specifying 'nmi_watchdog=0' at kernel command line." Add this option to your grub configuration, reboot, and the module should load.

• Windows 2000 hosts: Unfortunately a bug slipped into VirtualBox 1.3.2 that prevents it from executing on Windows 2000 hosts. This will be fixed in the next release. (Windows 2000 guests still work.)