Failed to open a session for the virtual machine (VirtualBox)

Was not using VirtualBox for some time and now found that it stopped working (as usual).

When running, the following error appears

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Some details

VT-d is enabled in BIOS

Host system is Windows 8

Version of

Text Version

Failed to open a session for the virtual machine Nebulla.

VT-x is not available. (VERR_VMX_NO_VMX).

Result Code: E_FAIL (0x80004005) Component: Console Interface: IConsole {db7ab4ca-2a3f-4183-9243-c1208da92392}

SOLVED

It was a conflict with Hyper-V. When it is installed, then Oracle Virtual Box can't run 64-bit virtual machines.

Dims

Posted 2013-05-30T08:42:34.080

Reputation: 8 464

Don't answer your own question inside it. Please, edit question, remove Solved section and answer your own question by providing full answer. Please, use Stack Exchange standard. Thank you. – trejder – 2016-09-06T18:49:31.397

vt-x and vt-d are 2 different things (this is vt-d: http://en.wikipedia.org/wiki/IOMMU). Make sure vt-x is enabled.

– magicandre1981 – 2013-05-30T17:54:04.573

Answers

Even if you have all the virtualization BIOS settings enabled, if you have Hyper-V turned in on Windows Features, VirtualBox will not detect VMX as available.

Use "Turn Windows features on or off", if you are able to remove Hyper-V. If you are unable to live with that, perhaps you can migrate your VMs to Hyper-V.

Andy Joiner

Posted 2013-05-30T08:42:34.080

Reputation: 363

An efficient way to handle this is described in https://blogs.msdn.microsoft.com/virtual_pc_guy/2008/04/14/creating-a-no-hypervisor-boot-entry/ and it basically creates a boot option for launching your Windows environment without Hyper-V running by using 'bcdedit'.

bcdedit /copy {current} /d "Microsoft Windows – no hypervisor"
bcdedit /set {guid from the previous command} hypervisorlaunchtype off

Once you do that, reboot and you should see a menu at startup that lets you choose to boot with or without Hyper-V enabled. Works on Windows 10.

Larry Smithmier

Posted 2013-05-30T08:42:34.080

Reputation: 164