Oracle Virtual box VM failed to start (VT-x is not available)


After importing cnMaestro OVA in Oracle Virtual box VM failed to start. An E_FAIL dialog is presented with.

VT-x is not available (VERR_VMX_NO_VMX)


VT-x features locked or unavailable in MSR.


Root Cause:

cnMaestro OVA is pre configured for 2 virtual processors and 64 bit Ubuntu as guest OS. Both of these requires “Hardware Virtualization (VT-x/AMD-V)”. If CPU does not support “Hardware Virtualization” or its disabled, then above error is presented. In some cases, though CPU supports virtualization certain vendors have disabled the virtualization extensions by default in their CPUs.


  • Check if your processors support hardware virtualization. Both Intel and AMD provide tools to check if your processor supports virtualization. If your CPU does not support virtualization, then hardware upgrade would be required else proceed with following steps if processor supports virtualization but its disabled in BIOS.
  • Reboot the computer and open the system's BIOS menu. This can usually be done by pressing the delete key, F1 key, F12 key or any other key depending on the system.
  • Open the Processor sub menu The processor settings menu may be hidden in the Chipset, Advanced CPU Configuration or Northbridge.
  • If you are not able to find required menu, then refer your manufacturer manual for BIOS.
  • Enable Intel Virtualization Technology (also known as Intel VT) or AMD-V depending on the brand of the processor. The virtualization extensions may be labelled Virtualization Extensions, Vanderpool or various other names depending on the OEM and system BIOS.
  • Enable Intel VTd or AMD IOMMU, if the options are available. Intel VTd and AMD IOMMU are used for PCI pass-through.
  • Select Save & Exit.
  • After Reboot, Open Virtual BOX VM is set to “Enable VT-x / AMD-V” Hardware Virtualization. This setting is visible by clicking on VM then Right Click > Settings > System > Acceleration