How do I get ubuntu to boot again after disk clone?

Question

This is a question about dual boot system with Windows 10 and and Ubuntu 18.04. The dual boot was setup with wubiuefi.

I cloned the boot disk to a new disk and then replaced it with the new disk. Ubuntu stopped booting after that. I would like to get it back on track.

When I boot my PC I get a grub menu with 4 options:

• Ubuntu
• Advanced options for Ubuntu
• Windows Boot Manager (on /dev/sdb2)
• System setup

If I choose Ubuntu options, I get the following text:

Booting a command list
error: no such device: B0ACCB58ACCB17AC
Press any key to continue..

On pressing any key system hangs.

If I choose the Windows option I get:

error: no such device: 62A5-4B98.
error: file `/EFI/Microsoft/Boot/bootmgfw.efi' not found.

Press any key to continue...

I still can log in to windows, if during the boot up process I select BIOS Boot options. When I do I see the menu:

• P0: WDC WD40EZRZ-00WN9B0
• P2: WDC WD4005FZEX-00Z4SA0
• Windows Boot Manager
• P1: CT1000MX500SSD1
• Xubuntu
• Enter Setup

If I select P0, P1 or P2 option I get a message about a missing boot record. If I select Xubuntu I get to the grub menu I described above. If I select Windows Boot Manager I can successfully boot to windows.

Here is what I see if select e on the Ubunutu line in grub:

setparams 'Ubuntu'
gfxmode $linux_gfx_mode
insmod gzio
insmod ntfs
set root='hd1,gpt4'
if [ x$feature_platform_search_hint = xy ]; then
  search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt4 --hint-efi=hd1,gpt4 --hint-baremetal=ahci1,gpt4 B0ACCB58ACCB17AC
else
  search --no-floppy --fs-uuid --set=root B0ACCB58ACCB17AC
fi
loopback loop0 /ubuntu/disks/root.disk
set root=(loop0)
linux /boot/vmlinuz-4.15.0-39-generic root=UUID=B0ACCB58ACCB17AC loop=/ubuntu/disks/root.disk ro rootflags=sync quiet splash $vt_handoff
initrd /boot/initrd.img-4.15.0-39-generic

How can I fix my grub so that I can boot to Windows and Linux via grub again?

Note: all the above I typed manually (no copy-paste from the boot screen), so my apologies for any typos

Answer 1

Your problem is that file system UUID values has changed after you cloned the disk, in particular, there were two changes that are affecting you, the windows file system UUID and the ubuntu one. Most information that you need to fix it is contained in this helpful question, however let's flesh out missing details.

When you boot and is presented with the grub screen, go to "Advanced..." and select the recovery mode. Once boot process has finished choose root shell. Your goal is to find out the new values for new windows one which used to be 62A5-4B98 and for new linux one which used to be B0ACCB58ACCB17AC.

Once in root shell use the following two commands:

fdsik -l
blkid

The first one will show you existing partitions, you should look for one that has a description of "EFI System" or similar. That's the partition you are looking for in the output of blkid. That will give you UUID for windows. Note that depending on your configuration you might have more than one such partition. Without knowing more I cannot tell you which one to choose, presumable you know what your disks contained and should be able to tell which other ones that you might have on your PC are irrelevant. The UUID will have familiar XXXX-XXXX format, so it should be easy to spot.

Similarly, you need to find out which partition is used to boot into linux. I'm guessing this would be on if the remaining once on the same disk. The best way to find out which one, is to temporary insert your old disk drive (make sure to switch off your PC before doing that) and running blkid on that. It should show you B0ACCB58ACCB17AC on one of the partitions, and you should be able to deduce which one on your new drive correspond to that. This is a bit of inexact science, but it's very hard to give the precise instructions, without seeing it all on the screen.

Reboot again and in the grub menu press e on the "Ubuntu" line. Substitute B0ACCB58ACCB17AC with the value you found for each occurrence and press F10 to continue booting.

The boot is going to fail though, since you used wubiuefi and need to mount your windows disk to load your linux one. In the Ctrl-Alt-F2 terminal you should see a prompt to press Enter to drop into a recovery session. Do it. Edit /etc/fstab and substitute 62A5-4B98 with the new value you found. Save, reboot, go through the same sequence of replacing B0ACCB58ACCB17AC again and now you should be finally able to boot into linux.

Once you are logged in edit /boot/grub/grub.cfg and find/replace all B0ACCB58ACCB17AC and all 62A5-4B98 on their new respective values. Save and run update-grub.

Now you should be able to login to either Windows or Linux via your grub menu.