2012-09-21, Fri

Solution to VirtualBox not working after OS X 10.8.2 update

Apple released the 10.8.2 update to Mac OS X a few days ago. It breaks VirtualBox, causing the following error to come up when you try to power on your virtual machine.

VT-x is being used by another hypervisor. (VERR_VMX_IN_VMX_ROOT_MODE).

VirtualBox can’t operate in VMX root mode. Please close all other virtualization programs. (VERR_VMX_IN_VMX_ROOT_MODE).

Result Code: NS_ERROR_FAILURE (0×80004005) Component: Console Interface: IConsole {1968b7d3-e3bf-4ceb-99e0-cb7c913317bb}

I’m on a Macbook Pro Retina, and I had the same problem. Downgrading to 10.8 fixes the issue and allows VirtualBox to run again.

To downgrade to 10.8,

  1. Grab a copy of the OS X 10.8 InstallESD.dmg.
  2. Use Disk Utility to restore to a USB drive (minimum 8gb).
  3. Boot from USB (Hold down Option key when booting).
  4. Make sure you’re disconnected from the Internet (prevents the installer from auto updating).
  5. Select “Reinstall Mac OS X”

Hope this helps someone out there.

Follow the issue on

Isaac Su



  1. Thank you! At last, all i could find were identical problems and no solutions. Thanks for a short ‘n’ sweet straight answer.

    Karl · Oct 4, 10:31 AM · #

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