[Solved] "Failed to open a session for the virtual machine"

Discussions about using Linux guests in VirtualBox.
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AlliumPorrum
Posts: 3
Joined: 27. Nov 2017, 21:21

[Solved] "Failed to open a session for the virtual machine"

Post by AlliumPorrum »

Hi!

I'm trying to re-run a few Ubuntu VM's from few years back, but I always just get this kind of an error:

Failed to open a session for the virtual machine MyVM.
VT-x is being used by another hypervisor (VERR_VMX_IN_VMX_ROOT_MODE).
VirtualBox can't operate in VMX root mode. Please close all other virtualization programs. (VERR_VMX_IN_VMX_ROOT_MODE).
Result Code: E_FAIL (0x80004005)
Component: ConsoleWrap
Interface: IConsole {872da645-4a9b-1727-bee2-5585105b9eed}


What might cause this issue?

My host is Win 10 + Virtual Box 5.2.2.
Last edited by socratis on 28. Nov 2017, 20:57, edited 1 time in total.
Reason: Marked as [Solved].
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: "Failed to open a session for the virtual machine"

Post by socratis »

AlliumPorrum wrote:VT-x is being used by another hypervisor (VERR_VMX_IN_VMX_ROOT_MODE).
AlliumPorrum wrote:My host is Win 10
After making 110% sure that Hyper-V is disabled in the Windows Features, you might want to make sure that Fast Boot is disabled and do a cold boot (i.e. shut down the host for a minute or two).

You also must make sure that nothing else is using Hyper-V, things like antivirus, debuggers, emulators, etc. Check out the article Diagnosing VirtualBox Hardening Issues to get some ideas...
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.
AlliumPorrum
Posts: 3
Joined: 27. Nov 2017, 21:21

Re: "Failed to open a session for the virtual machine"

Post by AlliumPorrum »

socratis wrote: After making 110% sure that Hyper-V is disabled in the Windows Features....
Ok, thanks Socratis, I did not know this... How exactly can I make sure that it is disabled?
viral
Posts: 4
Joined: 28. Jul 2017, 15:56

Re: "Failed to open a session for the virtual machine"

Post by viral »

Go to Control Panel (the real one, not the "Windows Settings" crap in W10), then "Programs and Features", then "Turn Windows features on or off." If Hyper-V is checked in there, it's enabled.
mpack
Site Moderator
Posts: 39156
Joined: 4. Sep 2008, 17:09
Primary OS: MS Windows 10
VBox Version: PUEL
Guest OSses: Mostly XP

Re: "Failed to open a session for the virtual machine"

Post by mpack »

You can also just go right click on the start button, run, "OptionalFeatures.exe". The "Hyper-V" box should be clear - not checked or shaded.
AlliumPorrum
Posts: 3
Joined: 27. Nov 2017, 21:21

Re: "Failed to open a session for the virtual machine"

Post by AlliumPorrum »

Ok, I checked the Hyper-V, and it was already disabled. Then, as instructed, I disabled the fast boot- option (which was ON), and that did it! Thank you very much for your help!
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: "Failed to open a session for the virtual machine"

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.
Avi_007
Posts: 2
Joined: 17. Nov 2018, 15:39

Re: [Solved] "Failed to open a session for the virtual machine"

Post by Avi_007 »

I checked all the diagnostics and. Hyper v disabled, fast boot is off and error not resolved. Can you please say what am i missing
mpack
Site Moderator
Posts: 39156
Joined: 4. Sep 2008, 17:09
Primary OS: MS Windows 10
VBox Version: PUEL
Guest OSses: Mostly XP

Re: [Solved] "Failed to open a session for the virtual machine"

Post by mpack »

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