error when trying to launch Virtualbox

[Al1_J]

Hello,
Virtualbox sudenly refuses to launch. The host is Ubuntu 18.04.4 LTS 64 bits. The error message is the following :



Échec de l'acquisition de l'object COM de VirtualBox.

Le programme va s'arrêter.



Document is empty.

Location: '/home/al1/.config/VirtualBox/VirtualBox.xml', line 1 (0), column 1.

/home/vbox/vbox-6.1.6/src/VBox/Main/src-server/VirtualBoxImpl.cpp[740] (nsresult VirtualBox::init()).

Code d'erreur : NS_ERROR_FAILURE (0x80004005)
Composant : VirtualBoxWrap
Interface : IVirtualBox {d0a0163f-e254-4e5b-a1f2-011cf991c38d}
Fonction appelée : IVirtualBoxClient {d2937a8e-cb8d-4382-90ba-b7da78a74573}

I reinstalled virtualbox but this did not solve the issue. I hope that someone here understands what is happening. Thanks.

[scottgus1]

This appears to be your problem:

Document is empty.

Location: '/home/al1/.config/VirtualBox/VirtualBox.xml', line 1 (0), column 1.

Reboot your PC so no Virtualbox processes or windows are running. Look in "/home/al1/.config/VirtualBox", and see if there is a "VirtualBox.xml-prev". If so rename 'VirtualBox.xml' to 'VirtualBox.xml-bad'. Then rename 'VirtualBox.xml-prev' to 'VirtualBox.xml'. Try Virtualbox and the guest.

[Al1_J]

This appears to be your problem:

Document is empty.

Location: '/home/al1/.config/VirtualBox/VirtualBox.xml', line 1 (0), column 1.

Reboot your PC so no Virtualbox processes or windows are running. Look in "/home/al1/.config/VirtualBox", and see if there is a "VirtualBox.xml-prev". If so rename 'VirtualBox.xml' to 'VirtualBox.xml-bad'. Then rename 'VirtualBox.xml-prev' to 'VirtualBox.xml'. Try Virtualbox and the guest.

Hello scottgus1.
Thank you for your help. I did what you recommended. Now I can launch Virtualbox, but my W10 virtual machine is mentioned as "inaccessible" and almost the same message as before appears :

Document is empty.
Location: '/home/al1/VirtualBox VMs/W10/W10.vbox', line 1 (0), column 1.
/home/vbox/vbox-6.1.6/src/VBox/Main/src-server/MachineImpl.cpp[758] (nsresult Machine::i_registeredInit()).
Code d'erreur :
NS_ERROR_FAILURE (0x80004005)
Composant :
MachineWrap
Interface :
IMachine {85632c68-b5bb-4316-a900-5eb28d3413df}

[scottgus1]

go to the guest's folder '/home/al1/VirtualBox VMs/W10', find W10.vbox and W10.vbox-prev and do the same name swap.

These two files that went empty get overwritten during normal operation of Virtualbox and the guest. To help prevent data loss during the overwrite, the present file is renamed to the -prev version, then the file is overwritten. It appears there was a glitch during the overwrite process.

[Al1_J]

It works !Thank you so much scottgus1 ! And thank you for the explanation about what occurred.

[scottgus1]

Great! Glad you're up and running!

[Al1_J]

Well, I could work again just once on the VM. The following attempt lead again to the same issue, with the same error message. Thus I did the same file names swaps (VirtualBox.xml and W10.vbox . Then I could launch Virtualbox but the VM cannot start. My screen stays like that :

I tried to swap back the W10.vbox file names but I got the same screen as above. Now I don't know what to do.

Edit: the screenshot can be viewed here : http://pix.toile-libre.org/upload/origi ... 478843.png

[scottgus1]

Looks like the image didn't come through. Use Upload Attachment, and if there is another Virtualbox error message, please let us know what it is.

[Al1_J]

Here is the screenshot attached.
There is no error message, just this screen lasting forever.

[scottgus1]

Power off the guest, then zip and post the guest's vbox.log, using Upload Attachment.

[Al1_J]

Here you are. Thank you for helping!

[scottgus1]

Please just send just the one log, so we don't have to guess which is which, or tell us what each log shows if you feel more than one log is necessary.

[scottgus1]

One log shows the guest booting into EFI, and then getting stuck. The "can't take a screenshot" errors just mean that the guest screen was not in a state to allow a Virtualbox screenshot-taker (possibly the Preview window) to work. It is not a deadly error, but it does mean the guest seized if it happens repeatedly like it does in your log.

You have bigger issues if your Virtualbox cannot shut down a guest without corrupting the xml files. Try a host disk check and a reinstall of Virtualbox. You may have to go to a backup of your host PC to get a good .xml and/or .vbox file.

[Al1_J]

Sorry, I did not know which log I had to send.
I did not mention that in the same period when the virtualbox issue first appeared, I received notifications from the host, that the hard disk was getting full. That's why I freed about 20 Go today. I did this after the second occurrence of the bug. I should have done this earlier. But your suggestion to check the host's disk makes sense.
I am now going to follow your last advices.

[Al1_J]

The host's disk is healthy. I tried to reinstall Virtualbox but nothing happened, probably because I already have the last version. Can I remove Virtualbox and install it again without losing my VM ?