I just finished installing 12.04 on my system, configuring it with LUKS and LVM.

I can open the encrypted position just fine in a recovery disk, but I just can't seem to get it to boot.

It waits quite a while for the root partition, then explodes with errors on how it couldn't find the root device:

ALERT! /dev/mapper/vgcryptotop-lvcryptotoproot does not exist. Dropping to a shell!

I then get the initramfs prompt. I have tried running cryptsetup to open the disk from here, but it replies that cryptsetup isn't found by the shell.

I think that somehow, the OS was installed without LUKS and/or LVM. How do I fix this problem? How can I test my theory?

1 Answer 1


Make sure dm-crypt.ko is in your initramfs. If it's NOT, it won't be able to mount the / filesystem and that's probably why you see the error.

chroot or just mount the /boot or / filesystem and do a /sbin/lsinitramfs initrd.img-$(uname -r)

You should see something like below (from a Debian wheezy box)

/boot# lsinitramfs initrd.img-`uname -r` | grep dm

If it's NOT, you may have to chroot into the system from a live CD (e.g. system rescue cd) and regenerate initramfs -> update-initramfs -u -k all.

Boot and see if it helps, if all good, you should be prompt to input the passphrase for the encryption key.

  • 2
    I ran into the issue and your answer helped; thanks. I think what happened is that the first time I did ´update-initramfs´, it had a warning saying my crypttab was invalid, and I didn't notice the warning. As a result, ´dm-crypt.ko´ was not installed. Fixing my crypttab and running this command again fixed my situation. Jan 18, 2015 at 3:59
  • If you're using a live Debian CD, update-initramfs is disabled. Use /usr/sbin/update-initramfs.orig.initramfs-tools instead.
    – z0r
    Jun 7, 2015 at 14:55
  • Instructions for getting to a chroot. You may also need to install lvm2 and cryptsetup in the live environment, and use them to gain access to your disks before chrooting.
    – z0r
    Jun 7, 2015 at 14:56
  • This must be out of date for more recent ubuntu. I'm missing dm-crypt.ko on the partition I'm trying to fix, but also on a working one. I'm working on Ubuntu 14.04 - not the latest.
    – mc0e
    Jun 14, 2016 at 17:20

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