Yesterday my Virtualbox guests were still running. Today I get the following error for all guests (windows or Linux).

Failed to open a session for the virtual machine win10.

The VM session was closed before any attempt to power it on.

Result Code: NS_ERROR_FAILURE (0x80004005)
Component: SessionMachine
Interface: ISession {7844aa05-b02e-4cdd-a04f-ade4a762e6b7}

I already tried to run sudo /sbin/vboxconfig, reinstalling from Software Manager, reinstalling following Cannot run virtual machines after upgrading virtualbox from 5.0 to 5.1 and upgrading to 5.2.12 r122591 and 5.2.14 r123301. The result was always the same.

My current kernel version is 4.15.0-24-generic #26-Ubuntu SMP.

$ VBoxManage list extpacks
Extension Packs: 1
Pack no. 0:   Oracle VM VirtualBox Extension Pack
Version:      5.2.14
Revision:     123301
Description:  USB 2.0 and USB 3.0 Host Controller, Host Webcam, VirtualBox RDP, PXE ROM, Disk Encryption, NVMe.
VRDE Module:  VBoxVRDP
Usable:       true 
  • 1
    Looks like you need to (re-)install Guest Additions correctly. Jul 8 '18 at 19:57
  • 1
    @DavidFoerster To install the guest additions I would need a running guest system which I don't have.
    – muclux
    Jul 8 '18 at 20:09
  • Sorry, I meant the Virtualbox Extension Pack. That's what the answers to the linked question say anyway. ;-] Jul 8 '18 at 20:13
  • ok, I got the extension pack 5.2.14 from virtualbox.org and opened it (as suggested) with VirtualBox. How can I verify now that it is really installed - because the guest still don't start?
    – muclux
    Jul 8 '18 at 20:17
  • The VirtualBox management interface should show you. How or from where did you install VirtualBox btw? And what's the output of dkms status? Jul 8 '18 at 20:21

I had similar issue on xubuntu 18.04 where my Virtualbox guests was to run windows 7. Although I had Virtualbox 5.2 installed previously that worked.

  1. I made sure that virtualbox-dkms was installed by running this command:

    dpkg -l | grep virtualbox-dkms
  2. Then I purged it and and reinstalled only dkms:

    apt-get purge virtualbox-dkms && sudo apt-get install dkms
  3. Then I ran the suggested command to rebuild the kernel:

    sudo /sbin/vboxconfig 

This is what worked for me.

  • Step 1 solved this error message for me on ubu 18.04
    – DMrFrost
    Aug 15 '19 at 9:17
  • 1
    @DMrFrost: that's impossible because dpkg -l doesn't install or uninstall anything. Anyway, I ran all three steps successfully, but I keep getting the same error. Oct 15 '19 at 8:13
  • This worked for me on U19.10. Thanks Jan 31 '20 at 14:55
  • simply running 'sudo /sbin/vboxconfig' prior to launching the virtualbox worked for me
    – cloudcell
    Apr 27 '20 at 1:36
  • This helped also for Xubuntu-20-focal with VirtualBox 16.1.16
    – rundekugel
    Dec 13 '20 at 16:57

After a long, friendly and fruitful chat with @DavidFoerster, it turned out that Microsoft and its weird update policy was the culprit!

David patiently guided me through the reinstallation of the VirtualBox packages from the Ubuntu repositories and check out the configuration (dkms, extension packages, etc.). At last, he asked me to try a new installation with a live ISO. It was then that I noticed that my "Default Machine Folder" defined in VirtualBox - File - Preferences - General was not usable. I knew that it was on a mounted NTFS used by the dualboot Win10 system. A closer look showed that at present it was mounted read-only, which prevented the virtual machines from starting (with a not very helpful error message).

As I recalled then, shortly after I had last successfully booted the VirtualBox guests, I had not only got Ubuntu updates, but I had also booted for the first time since long my native Win10 system. Apparently, Microsoft had then installed updates AND had reactivated the 'fast startup' option (which certainly had been deactivated before!) - so that later, back in Ubuntu, the NTFS file system was mounted in read-only mode, as Windows had not properly shut down.

Now that I have again deactivated the 'fast startup' option in Windows10, my guest systems are running again.

Thank you, David, for asking the right question which set me on the right track!

  • 1
    I get the same cryptic error on an Ubuntu host (no dual boot or anything), and the VM directory is a regular read-write one. Oct 15 '19 at 8:15
  • Definatley not the right answer here. Jun 11 '20 at 22:53

I have encountered the mentioned issue and I tried all the suggested solutions, but they didn't solve my problem.

In my case, I figured out that the VirtualBox.xml file (which is located under ~/.config/VirtualBox) seems to be empty and there was a file named as VirtualBox.xml-prev. So I moved second file, renamed as VirtualBox.xml in the same directory and my problem is solved.

  • worked like a charm - do you know why this is the case though.. what created the back up "prev" file? Jun 11 '20 at 22:55

Just had the same issue and figured out the problem and an easier solution... The problem was the usb settings... if you switched your usb settings back to 1.1 it would boot again... incase anyone else like me finds this post having the same problem... that solved it for me... but thanks for this post it led me to that solution...

  • USB was already set to 1.1 and I keep getting that useless error. Also, you may want to review your excessive usage of ellipses. Oct 15 '19 at 8:17

For me the issue was that I tried starting it with simply vboxmanage startvm ExampleVM but I didn't have X forwarding working, so it would presumably try to create a display and fail. Adding --type headless fixed the issue:

vboxmanage startvm ExampleVM --type headless

Of course, this only applies if headless is what you want to do.

I cross-posted this answer from a very similar question (same error code) at https://unix.stackexchange.com/a/641243/30731


Below commands Fixed for me (Ubuntu 18.04)

Reinstall the virtualbox-dkms

sudo apt install virtualbox-dkms

Restart the virualbox


The Answers given here, by the other AskUbuntu users, are already very good.
As an additional measure it might help if you download a suitable VirtualBox Extension Pack from the Downlads Page of the Virtualbox Web site.
Do this only if you know that you had the Extension Pack installed previously. (I think it enables a better USB access to VirtualBox guests).
The minor version number (for v6.1.18, thats the 6.1) of the Extension Pack should match the Minor version of your virtualbox installation.
I had an older Windows guest that refused to start because I had built a new host kernel, a new SSD to store, pending Windows upgrades, and tried to start a snapshot (I don't remember).
However a more decriptive error message ("Extension Pack too old"), better thanNS_ERROR_FAILURE (0x80004005) came up only after doing a start of a "cleaner", different Windows guest.

Maybe this is purely cosmetic, but worth a try.


Changing USB from 3.0 to 1.1 immediately fixed my inability to boot my Win10 guest under Ubuntu. Simple, easy solution.


After a freeze of Linux I had to do a "hard" restart of my Laptop. After reboot none of my VirtualBoxes was able to be started. I got the same error message with every Box: ns_error_failure 0x80004005.

Solution: Another regular restart of Linux
Sounds too simple, but it worked.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.