[Solved] Windows 10 1803 - VT-x is not available

Discussions related to using VirtualBox on Windows hosts.
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s-jones
Posts: 4
Joined: 16. May 2018, 22:55

[Solved] Windows 10 1803 - VT-x is not available

Post by s-jones »

Upgraded to 1803 a little while back. VirtualBox was working fine. Did a reboot today and am now getting a "VT-x is not available" when trying to start VMs.

Hyper-V is off.
WMI "select * from Win32_ComputerSystem" returns HypervisorPresent = True

Enabled Hyper-V, rebooted, disabled Hyper-V, rebooted. No change.
Added "EnableVirtualizationBasedSecurity" reg key, set it to 0, rebooted, no change.

Has anyone else run into this?
Last edited by socratis on 17. May 2018, 00:00, edited 1 time in total.
Reason: Marked as [Solved].
socratis
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Posts: 27330
Joined: 22. Oct 2010, 11:03
Primary OS: Mac OS X other
VBox Version: PUEL
Guest OSses: Win(*>98), Linux*, OSX>10.5
Location: Greece

Re: Windows 10 1803 - VT-x is not available

Post by socratis »

Did you re-install VirtualBox?
I need the exact error message. VT-x is not available is not the same as Hyper-V is in use.
Do NOT send me Personal Messages (PMs) for troubleshooting, they are simply deleted.
Do NOT reply with the "QUOTE" button, please use the "POST REPLY", at the bottom of the form.
If you obfuscate any information requested, I will obfuscate my response. These are virtual UUIDs, not real ones.
s-jones
Posts: 4
Joined: 16. May 2018, 22:55

Re: Windows 10 1803 - VT-x is not available

Post by s-jones »

Yes, I did an uninstall / reinstall of VirtualBox.
Failed to open a session for the virtual machine Windows 10.

VT-x is not available (VERR_VMX_NO_VMX).

Result Code: E_FAIL (0x80004005)
Component: ConsoleWrap
Interface: IConsole {872da645-4a9b-1727-bee2-5585105b9eed}
socratis
Site Moderator
Posts: 27330
Joined: 22. Oct 2010, 11:03
Primary OS: Mac OS X other
VBox Version: PUEL
Guest OSses: Win(*>98), Linux*, OSX>10.5
Location: Greece

Re: Windows 10 1803 - VT-x is not available

Post by socratis »

Please go thoroughly through the FAQ: I have a 64bit host, but can't install 64bit guests.

Those are guidelines, you have to use your judgement, don't expect the solution to pop out...
Do NOT send me Personal Messages (PMs) for troubleshooting, they are simply deleted.
Do NOT reply with the "QUOTE" button, please use the "POST REPLY", at the bottom of the form.
If you obfuscate any information requested, I will obfuscate my response. These are virtual UUIDs, not real ones.
s-jones
Posts: 4
Joined: 16. May 2018, 22:55

Re: Windows 10 1803 - VT-x is not available

Post by s-jones »

This fixed it:

Local Computer Policy > Computer Configuration > Administrative Templates > System > Device Guard > Turn on Virtualization Based Security to Disabled
socratis
Site Moderator
Posts: 27330
Joined: 22. Oct 2010, 11:03
Primary OS: Mac OS X other
VBox Version: PUEL
Guest OSses: Win(*>98), Linux*, OSX>10.5
Location: Greece

Re: Windows 10 1803 - VT-x is not available

Post by socratis »

Great! Thanks for the feedback. Marking as [Solved].
Do NOT send me Personal Messages (PMs) for troubleshooting, they are simply deleted.
Do NOT reply with the "QUOTE" button, please use the "POST REPLY", at the bottom of the form.
If you obfuscate any information requested, I will obfuscate my response. These are virtual UUIDs, not real ones.
s-jones
Posts: 4
Joined: 16. May 2018, 22:55

Re: [Solved] Windows 10 1803 - VT-x is not available

Post by s-jones »

Thanks for the pointer to the article. It was just very odd that it worked for about a week and a half before "breaking".
socratis
Site Moderator
Posts: 27330
Joined: 22. Oct 2010, 11:03
Primary OS: Mac OS X other
VBox Version: PUEL
Guest OSses: Win(*>98), Linux*, OSX>10.5
Location: Greece

Re: [Solved] Windows 10 1803 - VT-x is not available

Post by socratis »

Microsoft acts like one of those protective "mothers" that knows what's best for you, no matter if you want it or not... ;)
Do NOT send me Personal Messages (PMs) for troubleshooting, they are simply deleted.
Do NOT reply with the "QUOTE" button, please use the "POST REPLY", at the bottom of the form.
If you obfuscate any information requested, I will obfuscate my response. These are virtual UUIDs, not real ones.
LiamH
Posts: 4
Joined: 4. Jan 2017, 17:23

Re: [Solved] Windows 10 1803 - VT-x is not available

Post by LiamH »

After a recent administrator update of Windows 10 host OS I found that I could not start up the guest OS; I got exactly this message. It had been working for nearly a year previous to this update. I was able to resolve it following these instructions; I had to change two settings. For the benefit of those who like me know little to nothing about configuring Windows, I'm giving my complete steps.
  1. 4 panes (lower left)-> Gear (upper right "common utilities") -> Magnifying glass type "Group policy" -> Edit group policy -> following steps in MS documentation, set "Turn on Virtualization Based Security" to "Disabled" (it was set to "Enabled").
  2. Follow instructions here to disable Hyper-V by clicking on box filled black so that the fill was removed.
  3. Restart Windows
After that I was able to start up VBox and the guest OS as before without problem.
MyselfGr
Posts: 1
Joined: 5. Dec 2018, 10:16

Re: [Solved] Windows 10 1803 - VT-x is not available

Post by MyselfGr »

That thing drived me paranoid....

Searched everywhere for a solution but after few hours of trying and fail i came across someone mentioning about

Core Isolation is enabled

Which was the source of my headache.

Turned it off and VOILA...problem solved
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