I had the same error messages after I did a release-upgrade from Ubuntu 14.04 LTS to 16.04 LTS in a chroot (chroot as described in this German article) from a live system.
The error occurred before the password prompt. As the LVM volume group is usually within the encrypted volume, it must be a dm_crypt/LUKS configuration issue.
I found a solution here and will explain it below.
In my case, the name of the mapper of the encrypted volume was different from the name given in /etc/crypttab.
I picked the name of the luks mapper from the output of ls -l /dev/mapper, after opening the encrypted device with the the graphical file manager. In my case, the output was:
control
luks-87fc4c8e-017b-8482-cd09-7332fe351628
vgubuntu-root
vgubuntu-swap
Then, as root, I changed my /etc/crypttab (please note the beginning of the line) from:
sda5_crypt UUID=87fc4c8e-017b-8482-cd09-7332fe351628 none luks,discard
to:
luks-87fc4c8e-017b-8482-cd09-7332fe351628 UUID=87fc4c8e-017b-8482-cd09-7332fe351628 none luks,discard
Finally I updated my initramfs:
update-initramfs -u -k all
It was a bit confusing that these two names were different. One would assume that when the mapper is created, its name is taken from the crypttab. Anyway, it worked.
I did the whole stuff in a chroot, running a live system. It might also work from the busybox shell in which you drop after booting your system, but I haven't tried.
Best Answer
I managed to resolve this for my machines by adjusting the grub configuration like so:
In
/etc/default/grub, change:GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"toGRUB_CMDLINE_LINUX_DEFAULT="nomodeset"Then add this line:GRUB_TERMINAL_INPUT="console serial"Runsudo update-grubandrebootfor the changes to take effect.