Ubuntu
virtualbox-ose package

Explain "VirtualBox can't operate in VMX root mode" error

Asked by Thierry Carrez

When starting a virtual machine, VirtualBox will complain:

"Failed to start the virtual machine XYZ

VirtualBox can't operate in VMX root mode. Please disable the KVM kernel extension, recompile your kernel and reboot.
VBox status code: -4011 (VERR_VMX_IN_VMX_ROOT_MODE).

Result Code:
NS_ERROR_FAILURE (0x80004005)
Component:
Console
Interface:
IConsole {e3c6d4a1-a935-47ca-b16d-f9e9c496e53e}"

What does this mean exactly ? What should I do ?

Question information

Language:
English Edit question
Status:
Solved
For:
Ubuntu virtualbox-ose Edit question
Assignee:
No assignee Edit question
Solved by:
Thierry Carrez
Solved:
Last query:
Last reply:
Revision history for this message
Thierry Carrez (ttx) said : 		#1

This error is because two virtualization technologies are present on your system (KVM and VirtualBox).

If you need both installed, you can disable KVM temporarily by running:
$ sudo /etc/init.d/qemu-kvm stop

If you don't really need KVM, you can uninstall it by running:
$ sudo apt-get purge qemu-kvm

Revision history for this message
Byron Gibson (byrongibson) said : 		#2

What's the difference between:

sudo stop qemu-kvm

and

sudo /etc/init.d/qemu-kvm stop

?

The forrmer (along with its similar 'start' version) seems to work for this problem as well. Is one more appropriate that the other?

Revision history for this message
Thierry Carrez (ttx) said : 		#3

It's the same. "/etc/init.d/qemu-kvm stop" calls "stop qemu-kvm".

Revision history for this message
Byron Gibson (byrongibson) said : 		#4

Thanks, still learning my way around the internals.