Frequently Asked Questions (FAQ) for end users (User FAQ)

Here you can find common questions, frequently asked on the VirtualBox mailing lists and IRC channel, along with their answers. Please consult this list every time you run into a problem that is not described in the User Manual.

Linux hosts

• If you get a message saying "VirtualBox kernel driver not accessible, permission problem" when starting VirtualBox right after 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.)

• 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.

• Debian packages: If the installation of the !VirtualBox_*.deb package was not successful because the compilation of the kernel module fails, it might not be possible to remove the package nor to install other packages as the pre-remove (prerm) script of the package (which is executed prior to package removing or upgrading) aborts with an error "(Kernel module not found)...fail!". In that case do the following:
  • Edit /etc/init.d/virtualbox and change line 129 from 'exit 1' to 'exit 0'
  • Reinstall the virtualbox package by 'dpkg -i <the VirtualBox package for your distribution>'. An installation failure of this package is expected.
  • Edit /var/lib/dpkg/info/virtualbox.postinst and change line 39 from 'exit 1' to 'exit 0'
  • Execute 'dpkg --configure --pending'
  • The package should now be installed successfully. However, the kernel module is still not compiled. Before you will be able to execute VirtualBox you have to create a kernel module for your current kernel, as described in the User Manual (see our ​Downloads section).

Windows hosts

• 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. In the meantime you can install this test build that also fixes the problem.

Windows Vista guests

• Unfortunately Microsoft dropped support for the AMD PCnet card in Vista that we implement for virtual machines. As a result, Vista guests initially have no networking. To fix that, install ​the NDIS5 AMD driver in the guest. As you have no networking in the Vista guest, you cannot download the file from the guest, and you can't access it over the network either. So the easiest way to access the file is to create an ISO CD-ROM from it and mount that in the guest. On linux, this can be easily done with mkisofs -o name-of-target-iso -R -J /path/to/folder/with/amd/driver/file.