VT-x is not available (VERR_VMX_NO_VMX) when starting ubuntu in Virtualbox

It is a known issue when running 64-bit VMs in VirtualBox 6.x on Windows 10.

The culprit is Windows Defender Application/Device Guard.

• Method 1

To disable it go to Local Group Policy Editor (Win+R->gpedit.msc) and disable Turn on Virtualization Based Security

Local Computer Policy > Computer Configuration > Administrative Templates > System > Device Guard > Turn on Virtualization Based Security

Disable Virtualization Based Security in Local Group Policy Editor

Then you need to run the below commands in command line as an Administrator:

mountvol X: /s
copy %WINDIR%\System32\SecConfig.efi X:\EFI\Microsoft\Boot\SecConfig.efi /Y
bcdedit /create {0cb3b571-2f2e-4343-a879-d86a476d7215} /d "DebugTool" /application osloader
bcdedit /set {0cb3b571-2f2e-4343-a879-d86a476d7215} path "\EFI\Microsoft\Boot\SecConfig.efi"
bcdedit /set {bootmgr} bootsequence {0cb3b571-2f2e-4343-a879-d86a476d7215}
bcdedit /set {0cb3b571-2f2e-4343-a879-d86a476d7215} loadoptions DISABLE-LSA-ISO,DISABLE-VBS
bcdedit /set {0cb3b571-2f2e-4343-a879-d86a476d7215} device partition=X:
mountvol X: /d

where X: is your unused drive letter (can be any other drive letter)

Reboot you computer and confirm disabling Device Guard and Virtualization Based Security by pressing F3 at boot. After that your virtual machines will be working again.

• Method 2

Another way to disable Device Guard is to use PowerShell script.

Download the script from Microsoft: https://www.microsoft.com/en-us/download/details.aspx?id=53337

Run the script as an Admin:

.\DG_Readiness.ps1 –Disable -AutoReboot

I found the answer and like to share with you .

1.Enable Virtualization during your BIOS time

2.Disable the Hyper-V role through Settings(problem faced by me)

a)Right click on the Windows button and select ‘Apps and Features’.

b)Select Programs and Features on the right under related settings.

c)Select Turn Windows Features on or off.

d)Select Hyper-V and disable it

I found the answer and like to share with you .

1.Enable Virtualization during your BIOS time

2.Disable the Hyper-V role through Settings(problem faced by me)

 a)Right click on the Windows button and select ‘Apps and Features’.

 b)Select Programs and Features on the right under related settings.

 c)Select Turn Windows Features on or off.

 d)Select Hyper-V and disable it

Please check the following link: https://stackoverflow.com/a/38111013/15374795

This answer belongs to -- credit Tj Kellie please do not add like for me.

Note: open Command Prompt by right click on that and click on "Run as administration".

To turn Hypervisor off, run this from Command Prompt (Admin) (Windows+X):

bcdedit /set hypervisorlaunchtype off

and reboot your computer. To turn it back on again, run:

bcdedit /set hypervisorlaunchtype on

If you receive "The integer data is not valid as specified", try:

bcdedit /set hypervisorlaunchtype auto

Important note: after turning off the Hypervisor and restarting the system it is mandatory to turn on the Hypervisor because with out Hypervisor you can not use the git repository on your windows.