after upgrade to 16.04: "ALERT! /dev/mapper/laptop--hp-root does not exist."

[mandavi2]

After I upgraded from 14.06 to 16.06 all new kernels would not work anymore. Despite my entire harddisk being encrypted via LUKS I'm not asked for a password. Instead I get following messages:

Begin: Running /scripts/local-block ... lvmetad is not active yet, using direct activation during sysinit
Volume group "laptop-hp" not found
Cannot process volume group laptop-hp
done.
That gets repeated many times before I get:

Gave up waiting for root device. Common problems:
...
ALERT! /dev/mapper/laptop--hp-root does not exist. Dropping to a shell!

Old kernels booted just fine until I removed them by accident. Yeah, congrats, I know...

My configuration is shown by the output of Boot Info Scrip (https://paste.ubuntu.com/23870703/)t.



So I chrooted from a USB-Image and installed older kernels. But I get the same error message now with them too.
I chrooted again to rebuild GRUB2 which went just fine, but didn't change anything.
I tried 'update-initramfs -k all -c' but it didn't change anything.
I tried to make the volumes available in initramfs like this guy did (https://ubuntuforums.org/showthread.php?t=1632033) after I'm dropped to a shell via 'cryptsetup luksOpen /dev/sda5 sda5_crypt' but initramfs tells me it doesn't know the command


Do I need to add things to GRUB via insmod to have cryptsetup in the initramfs shell?
Or how do I proceed from here?

[mandavi2]

I'm a little stuck here...
To decrypt my LUKS drive I seem to need cryptsetup which is provided by the module dm-crypt. I don't have that installed in /grub/i386-pc/.

It says on the project page (https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt) this tool is only for kernels below 4.x. So wouldn't it need to be installed on my machine as long as I still have 3.x kernels? And how is all the decryption done in 4.x kernels?

Any help is appreciated...

[mandavi2]

I was able to solve it by chrooting into my system and changing /etc/crypttab from


sda5_crypt UUID=c990132c-5b5c-44a4-8c73-dfa0b247e0ad none luks
to


luks-c990132c-5b5c-44a4-8c73-dfa0b247e0ad UUID=c990132c-5b5c-44a4-8c73-dfa0b247e0ad none luks

How your device is called you find out by issuing:

ls /dev/mapper/

control laptop--hp-root laptop--hp-swap_1 luks-c990132c-5b5c-44a4-8c73-dfa0b247e0ad


to have your /boot partition updated you need to

sudo update-initramfs -u all
and during boot I was asked for my password and booting worked again.