Ubuntu – Virtualbox – Failed to open a session for the virtual machine


I installed VirtualBox via Software Center. When I try to load a VM, getting an error exactly like this:

Error window

After I googled this error, found many different solutions, none of them were helped my situation. Also I removed all packages associated with VirtualBox, then downloaded and installed the latest package which I downloaded from Oracle repositories. Nothing is changed.

Additional Information:

  • OS : Ubuntu 12.04 64-bit
  • VM : Linux Mint 14 Cinnamon/MATE 64-bit

I created new vdi disk and tried to start it from .iso image.

Virtualbox Settings:

  • Num of processors : 4
  • Memory : 512 MB
  • Video Memory : 128 MB
  • 3D Acceleration: Enabled

Best Answer

The error message is pretty self explanatory. The VM you are trying to start needs hardware virtualization enabled. See the follwing Q&A on how to do so (provided your CPU is capable of this):

If this does not resolve the issue, the following steps may help:

  • Reboot the host OS
  • Try with fewer virtual CPUs starting from 1 only
  • disable VT-x settings in VBoxManager (reported to worked but I doubt this)
  • on a Hewlett Packard machine hardware VT-x could only be achieved with a BIOS update (source superuser.com)
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