Frequently Asked Questions 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.

Note that we update the User Manual (online ​here) on a regular basis, and information that first shows up on this page is moved to the User Manual regularly. As a result, please do check the User Manual also, especially the "Troubleshooting" section.

Also make sure to check whether you are running the latest version of VirtualBox.

This particular FAQ is for end-user issues only; you may want to look at the Developer FAQ and Licensing FAQ for additional topics.

How to get help

Note that support for non-paying customers is done on a best-effort basis. Note further that as the reporter of a problem, it's your responsibility to provide accurate information. Below are key pieces of data you should provide when requesting help from a ​mailing list or when reporting a bug in the ​public bug tracker.

Environment:

• Version of VirtualBox installed (e.g. 3.1.2)
• Type and version of the Host Operating System (e.g. openSUSE 11.2, Windows XP SP3, etc.)
• Type and version of the Guest OS

Problem:

• What are you trying to accomplish
• What did you expect and what was the result?

Attempted Resolutions:

• Have you searched the User Manual?
• What have you attempted and what was the result of each attempt?

Do not post VBox.log files to a mailing list -- better open a bug report (​search for existing bugs before!) and attach the VBox.log file there.

General

• VBoxManage modifyhd --compact crashes or corrupts .the vdi image
  There is a bug in VirtualBox 2.2.2 which is fixed in later releases. Don't use this command with release 2.2.2 or your .vdi image might get corrupted!

• Sometimes VirtualBox fails to start with a message on the lines of

  Failed to create VirtualBox COM object
   Callee RC: 0x80470007
  

  This usually means that the VirtualBox COM server was unable to start up, and is often a sign of problems in your installation of VirtualBox. In many cases this problem can be solved simply by reinstalling VirtualBox. Reinstalling will simply set up the VirtualBox program files again, and will not affect any virtual machines which you have created.

If this does not help, and you wish to investigate the problem further yourself, try starting the VirtualBox COM server (the program VBoxSVC in the VirtualBox program folder) from a command prompt or a DOS box. You may be able to see what is going wrong from error messages when the server starts.

Please do not open bug reports when you get this error before you have tried the other available support channels (​forums, mailing lists and IRC).

• "How come it doesn't detect my nVidia/ATI/whatever graphics card?"

Because the guest sees a virtual graphics card, not the host graphics card. The virtual graphics card provides the necessary VESA and VGA features to make the guest operative systems work OK. Additional features, like higher resolutions, is provided by the graphics driver included with the guest additions. More details on how to install guest additions and features of the virtual graphics card can be found in the manual.

• "Where is the guest additions ISO file?"
  • Windows: C:\Program Files\Oracle\VirtualBox\additions\
  • Mac OS X: /Applications/VirtualBox.app/Contents/MacOS/
  • Linux: /usr/share/virtualbox/additions or /opt/VirtualBox/additions
  • Solaris: /opt/VirtualBox/additions

The guest additions ISO file is included with all packages from ​virtualbox.org. The install locations differ with the exact package, and if you select a different installation base path they are also different.

Linux hosts

• Problems with network interfaces after installing or rebuilding the VirtualBox drivers: this is likely to be caused by a problem in the dkms tool. You can work around this by changing the line

  /sbin/udevadm trigger
  

  in the dkms script (/usr/sbin/dkms on Ubuntu) to

  true
  

• dkms status fails after VirtualBox was removed (deb/rpm): The VirtualBox 1.6.0 and 1.6.2 packages did not properly de-register from dkms during uninstallation. To work around this problem do

  rm -rf /var/lib/dkms/vboxdrv
  

  after you uninstalled a VirtualBox deb/rpm package.

• The same problem happens after uninstalling / upgrading from VirtualBox 2.1.0. The solution is

  rm -rf /var/lib/dkms/vboxnetflt
  

• USB: if you are having trouble accessing USB devices in a guest, make sure that you are a member of the vboxusers system group.

• Tickless Linux timer: VirtualBox currently does not work well on Linux kernels with tickless timer support (CONFIG_NO_HZ enabled). We are investigating the problem but in the meantime you should disable the tickless timer by disabling that config option or by adding nohz=off to the Linux kernel command line.
  Starting with VirtualBox 1.5.6 the Linux kernel module knows the parameter force_async_tsc. Try loading the kernel module with

  modprobe vboxdrv force_async_tsc=1
  

  and see if that helps to improve things for you.
  (Should not be necessary anymore since VirtualBox 1.6.0)

• If you get a message saying "VirtualBox kernel driver not accessible, permission problem" when starting VirtualBox immediately after installation, make sure that your user account is a member of the vboxusers group. This group is created when VirtualBox is installed, but you will need to manually add all users to it who are to be allowed to run VirtualBox. The documentation accompanying your Linux distribution should provide information about how to do this. If not, the following should also work on most Linux systems. These commands should be run as the Administrator user from the command line.

  # groups <login name>
  [Shows a list of groups for that login name]
  # useradd <login name> -g <first group in list> -G <second group>,<third group>,...,vboxusers
  

  These changes will only take effect after the users have logged out and back in again.

• If the kernel module refuses to load with a message saying "Error inserting vboxdrv: Invalid argument", check (as root) the output of the "dmesg" command, and see "Troubleshooting" -> "Linux hosts" in the User Manual for solutions.

Linux/Solaris guests

• If the scroll button on your mouse does not work in the guest, try adding the following lines to the mouse section in your xorg.conf file:

  Option "Buttons" "5"
  Option "ZAxisMapping" "4 5"
  

Mac OS X hosts

• Although the manual claims 64-bit support for VirtualBox 2.0.0 this feature is not yet available for Mac OS X hosts.

FreeBSD guests

• FreeBSD guests do not properly detect the network card which is selected by default for new VMs (PCNet-Fast III). Please select PCNet-PCI II for *BSD guests. Furthermore, edit /etc/rc.conf and add ifconfig_le0="DHCP". Then run /etc/netstart.

• Over high CPU utilisation in FreeBSD guests may sometimes be fixed by adding the line

  kern.hz="100"# Set the kernel interval timer rate
  

to the file /boot/loader.conf.

Windows hosts

• If you configure a VM to use NAT networking (the default), the DNS relay in VirtualBox forwards all DNS queries to the first configured DNS server. Unfortunately on Windows the first configured DNS server is frequently not working (e.g. because it corresponds to a currently not connected interface). To work around this problem, configure a working DNS server in the network configuration inside the guest OS.

• Windows Vista hosts might show an error about a COM server not being accessible. This is a problem of our installation routine which we have not figured out yet. To fix the problem, open a command prompt shell and enter:

  cd \Programs\Oracle\VirtualBox
  VBoxSVC.exe /ReRegServer
  regsvr32.exe VBoxC.dll
  

  (Should not occur with current versions anymore)

• Installing the guest on fixed size disk images. Until version 1.5.4, VirtualBox creates a sparse file if the user selects 'fixed size' when creating a virtual disk image. That means that the file is created and its length on the real hard disk is defined but the file content is still not allocated. When trying to install a guest OS on this image, the first write accesses to a sector in the middle of the image will be delayed for a long time on Windows hosts. This might confuse the guest and make installing a guest impossible (for example, creating a partition fails). Starting with VirtualBox 1.5.6 we will write the whole file once during creation. Users of current versions should select a dynamically expanding image which does not have this limitation.
  (Fixed since VirtualBox 1.5.6)

Windows Shared Folders

• I cannot see my newly created shared folder under "My Network Places". Under Windows 2000 they're visible, but not under Windows XP / Windows Vista. This is because of the standard settings of these two.
  To get it working the way it was, just do the following steps:
  1. Open the Explorer
  2. In the menu go to "Tools" and select "Folder Options"
  3. Under tab "General" activate "Use Windows classic folders"

Now the "Entire Network" as well as the shared folder entries are visible again.

Windows minidumps

To debug application crashes on Windows hosts and guests, minidumps are very helpful. Please have a look at ​http://support.microsoft.com/kb/315263. If VirtualBox crashes on a Windows host or a Windows guest application crashes please add the appropriate minidump to the bug report.

Windows 98 guests

• High CPU load while running Windows 98 Windows 98 does not execute the 'hlt' instruction, which temporarily turns off the CPU, when it has no work to do. Download and install rain20 from ​here.

• Poor graphical output in Windows 98 Unlike more modern systems, Windows 98 does not come with a driver which will work with the VirtualBox graphics card, so it falls back to using it as a 16 color VGA card. While we do not provide Guest Additions for Windows 98, the Display Doctor 7 Beta suite by the company SciTech does contain a driver which will allow you to use higher color and resolution graphics modes. Please note that neither Oracle nor SciTech support nor accept liability for the use of this program.

Display Doctor 7 Beta requires activation codes to work. We understand that the free activation code for Display Doctor 6 also applies to version 7 Beta: ​http://www.scitechsoft.com/ftp/sdd/regcodes.txt.

You might also want to look at the following site pointed out by users of VirtualBox, which also provides VESA drivers for Windows 98: ​http://www.bearwindows.boot-land.net/vbe9x.htm. Please be aware that Oracle provides this link in good faith, but cannot take responsibility for the site or the software which it refers to.