I migrated my noteboook from Windows 10 to Ubuntu 18.04 recently. I wanted to keep my two virtual machines so I copied their Folders containing their .vbox .vbox-prev and .vdi files (Looking back I should have used the integrated export functionality). When I try to start the machines now on Ubuntu 18.04 Virtual Box aborts on start up with the following error message:

VD: error VERR_FILE_NOT_FOUND opening image file '/home/user/VirtualBox VMs/Ubuntu Mate 16.05/Ubuntu Mate 16.05.vdi' (VERR_FILE_NOT_FOUND). 

Have I missed to copy something or is this related to the change of the operating system?

Is it possible to restore the virtual machines?

The vbox.log file:

00:00:01.798459 VirtualBox VM 6.0.0 r127566 linux.amd64 (Dec 18 2018 13:18:17) release log 00:00:01.798461 Log opened 2018-12-24T14:01:24.737853000Z 00:00:01.798462 Build Type: release 00:00:01.798464 OS Product: Linux 00:00:01.798465 OS Release: 4.15.0-43-generic 00:00:01.798465 OS Version: #46-Ubuntu SMP Thu Dec 6 14:45:28 UTC 2018 00:00:01.798480 DMI Product Name: 20H2S00700 00:00:01.798484 DMI Product Version: ThinkPad E470 00:00:01.798513 Host RAM: 15944MB (15.5GB) total, 13975MB (13.6GB) available 00:00:01.798515 Executable: /usr/lib/virtualbox/VirtualBoxVM 00:00:01.798516 Process ID: 8578 00:00:01.798516 Package type: LINUX_64BITS__UBUNTU_18_04 00:00:01.807559 Installed Extension Packs: 00:00:01.807572 Oracle VM VirtualBox Extension Pack (Version: 6.0.0 r127566; VRDE Module: VBoxVRDP) 00:00:01.808413 Console: Machine state changed to 'Starting' 00:00:01.808615 Qt version: 5.9.5 00:00:01.808625 X11 Window Manager code: 2 00:00:01.810852 Console: Machine state changed to 'PoweredOff' 00:00:01.814111 GUI: Show mini-toolbar for window #0 00:00:01.820202 Power up failed (vrc=VINF_SUCCESS, rc=NS_ERROR_FAILURE (0X80004005)) 00:00:01.838190 GUI: Adjust mini-toolbar for window #0 00:00:01.838310 GUI: Resize mini-toolbar for window #0 to 1920x1080 00:00:01.838358 GUI: Move mini-toolbar for window #0 to 0x0 00:00:01.838998 X Server details: vendor: The X.Org Foundation, release: 11906000, protocol version: 11.0, display string: :0 00:00:01.839007 Using XKB for keycode to scan code conversion 00:00:02.321204 GUI: Aborting startup due to power up progress issue detected... 

2 Answers

1. I removed the hard disk from VM setting and try to add it again but not worked.
2. then I closed the VBox application and open it again it gives me a message that one of the hard drives did not exist when I looked to the virtual media manager it points to the same hard disk then I release the hard disk.
3. and go to the VM settings and insert the hard disk again and worked.

my solution (and my problem was) was just slightly different then the solution of @Mohannd here.

i got:

I reinstalled KUbuntu and dont changed my virtual machines (in the second HDD)

Whey I try to start the machines now on Ubuntu 20.04 Virtual Box aborts on start up with the following error message:

Runtime error opening '/media/x/dev_n/VirtualBox-Machines/kubuntu ava in 0ad/kubuntu ava in 0ad.vbox' for reading: -102 (File not found.). /build/virtualbox-9t4MJt/virtualbox-6.1.16-dfsg/src/VBox/Main/src-server/MachineImpl.cpp[754] (nsresult Machine::i_registeredInit()). Fehlercode: NS_ERROR_FAILURE (0x80004005) Interface: IMachine {85632c68-b5bb-4316-a900-5eb28d3413df} 

I guessed that I just need to correct the user number (1000 is good). Unfortunately, that was not the case, as can be seen here:

sudo ls -n
-rw------- 1 1000 1000 14448 Mär 14 11:50 'kubuntu ava in 0ad.vbox'
....

Virtual Box reading Error -102 File not found after reinstall Ubuntu

I just closed the VBox application and open it again.