virtualbox.org

Read the manual and searched the forums and finally resorting to posting here.

I am running a very recent version of virtualbox - 5.1.2 r108956 on mint. Recently upgraded to Win10. Everything was fine until i needed to expand the size of the Win10 machine hard drive.

So i decided to do some maintenance. first I deleted some snapshots and after the usual merging virtualbox indicated a success. Next up, went to do a size increase and ran "VBoxManage modifyhd New\ Win8-disk1.vdi --resize 82000". system was previously about 50 GB. Again no issues.

Then just went on to boot into Win10 and get the error "Fatal: Could not read read from the boot medium! system halted." Big mistake, forgot to backup my VDI file before this. So before i did anything else, took a backup of this.

The proceeded to try and resize the corrupt VDI a couple more times and the resize operation always went through without a hitch. but cannot boot. Now, I tried to see if I could fix this and booted into the VM using a live ubuntu CD and ran gparted. It said there was no partition and no partition table on the disk. With no clues, decided to come here to see if there is a fix for my issue.

Below are the last few lines from the log, but not helpful at all. Am wondering if I ran into a corner case by deleting the snapshots and expanding the image size, without booting in between. Any pointers are greatly appreciated. Thanks!
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00:00:00.638688 GUI: 2D video acceleration is disabled
00:00:00.638704 GUI: HID LEDs sync is not supported on this platform
00:00:03.017926 PIT: mode=2 count=0x10000 (65536) - 18.20 Hz (ch=0)
00:00:03.018187 VMMDev: Guest Log: BIOS: Boot : bseqnr=1, bootseq=0312
00:00:03.018575 VMMDev: Guest Log: BIOS: Boot from Hard Disk 0 failed
00:00:03.018773 VMMDev: Guest Log: BIOS: Boot : bseqnr=2, bootseq=0031
00:00:03.018945 VMMDev: Guest Log: BIOS: Boot from Floppy 0 failed
00:00:03.019137 VMMDev: Guest Log: BIOS: Boot : bseqnr=3, bootseq=0003
00:00:03.019658 VMMDev: Guest Log: BIOS: CDROM boot failure code : 0003
00:00:03.019815 VMMDev: Guest Log: BIOS: Boot from CD-ROM failed
00:00:03.020654 VMMDev: Guest Log: Could not read from the boot medium! System halted.
00:00:03.024371 Display::handleDisplayResize: uScreenId=0 pvVRAM=0000000000000000 w=720 h=400 bpp=0 cbLine=0x0 flags=0x1
00:00:03.024444 GUI: UIFrameBufferPrivate::NotifyChange: Screen=0, Origin=0x0, Size=720x400, Sending to async-handler
00:00:03.024519 GUI: UIMachineView::sltHandleNotifyChange: Screen=0, Size=720x400
00:00:03.024537 GUI: UIFrameBufferPrivate::handleNotifyChange: Size=720x400
00:00:03.024553 GUI: UIFrameBufferPrivate::performResize: Size=720x400, Directly using source bitmap content
00:00:43.620410 GUI: UIMachineViewFullscreen::adjustGuestScreenSize: Adjust guest-screen size if necessary.
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Trying to give it a bump to see if any of the knowledgeable folks here can help out.

Not sure if this is a host issue or a guest issue. If it is more relevant in the linux hosts sub, will x-post there. Thanks in advance!

I can't think of much to say about your problem, or I'd have already commented.

It's a guest issue, or it would be VirtualBox on the host which complains, not the guest OS.

VirtualBox is happy, but Win10 doesn't like something about the enlarged disk. Unfortunately it's impossible for me to know what that something is from here. All you can do is restore from a backup. No backup? Then it's probably game over - that is after all why we make backups.

If you know (exactly) what size the disk was before then you could try reducing it back to the original size using vidma, and see if that helps. Vidma is an unsupported third party tool whose main claim to fame is that it can be used to un-enlarge a VDI, provided you haven't filled the enlarged sectors yet. Vidma works in-place, so make sure you make a backup before trying it.