VirtualBox 6.1.32 r149290 (Qt5.12.8) Ubuntu 20.04.4 LTS

Today, after booting my Ubuntu laptop, I can't see any virtual machines. My VM list is empty. My Media list in VBox is empty too.

When I try to add VM from disk (folders with machines still exists) I see message: "Failed to open virtual machine located in /home/krzysiek/VirtualBox VMs/mymachinename/mymachinename.vbox.

A differencing image of snapshot {d9534ca2-48ff-40a8-a307-5ae996b6af94} could not be found. Could not find an open hard disk with UUID {21d363f7-f0ed-491d-a588-b4c71efa6976}.

Result Code: NS_ERROR_FAILURE (0x80004005) Component: SnapshotMachine Interface: IMachine {85632c68-b5bb-4316-a900-5eb28d3413df} Callee: IVirtualBox {d0a0163f-e254-4e5b-a1f2-011cf991c38d}"

EDIT: But I see this diff drive:

krzysiek@myUbuntuBox$ ls -al
total 72658432
drwx------ 2 krzysiek krzysiek        4096 kwi  7 19:24 .
drwx------ 4 krzysiek krzysiek        4096 kwi  7 19:25 ..
-rw------- 1 krzysiek krzysiek  4332766354 kwi  4 13:05 2022-04-04T11-05-10-902702000Z.sav
-rw------- 1 krzysiek krzysiek  4013965272 kwi  7 19:25 2022-04-07T17-24-58-411845000Z.sav
-rw------- 1 krzysiek krzysiek 46087012352 kwi  4 13:05 {21d363f7-f0ed-491d-a588-b4c71efa6976}.vdi
-rw------- 1 krzysiek krzysiek 19972227072 kwi  7 19:24 {d818945f-e028-41cb-817a-ebe5c24578b2}.vdi

enter image description here

  • Hello. The missing drive message may be a clue.
    – David
    Apr 12 at 11:23
  • Sorry all I see in that is a stream of numbers. From your question there is this. <Could not find an open hard disk with UUID>
    – David
    Apr 12 at 11:53
  • OK, but how is it possible that the file disappeared by itself? All files because all machines have the same problem? Apr 12 at 12:04
  • Like I said in the first comment it looks like a drive issue. Dead or dying.
    – David
    Apr 12 at 12:08
  • It’s clear from your question that you cannot see your VM’s or VM media in the VB application GUI. Can you see the media files in what ever file manager you use? Are those media files on the same partition as your system? If they are on another partition or device it that mounted correctly. Might be helpful to see the output of lsblk
    – PonJar
    Apr 12 at 14:27

1 Answer 1


OKAY. I had to manually add machines [Menu: Machine --> Add] to Virtualbox's GUI in the correct order. Since the machines were created as clones of others, the order in which they were added was critical. I am saved! :) The question remains, of course: why have machines disappeared from the machine manager? It is a mystery to me.


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