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CluelessNoob
Asked: 2024-05-06 02:16:24 +0800 CST

Can't install Kubuntu 24.04 or Lubuntu 24.04 in encrypted partition

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I tried installing these several times, but the same error keeps occurring every time. During installation, I selected manual partitioning, created an ext4 partition, checked the encrypt box, entered a passphrase, selected / as mount point, and proceeded with the installation. But after reboot when it asks for the encryption passphrase, and the passphrase is entered, it immediately shows an error like this:

error: Invalid passphrase.
error: disk 'cryptouuid/abc123...' not found.
Entering rescue mode...
grub rescue>

I am already using an encrypted installation of Lubuntu 22.04 as my main OS, and when I mistype the passphrase sometimes, it takes a few seconds before showing an error. But this time with 24.04, the error is almost instant without any delay, which makes me assume it is not even trying to decrypt.

Yes, I made sure the passphrase is correct. And I also made sure to create extra partitions when it was necessary (e.g. 8 MB unformatted when I tried with BIOS, or 300 MB fat32 when it was with UEFI, etc). I even tried good old MBR with no extra partition. I even tried selecting btrfs instead of ext4. Same error every time.

I've tried both Kubuntu 24.04 and Lubuntu 24.04 in VirtualBox, and they both have this same problem. I even tried Kubuntu 24.04 in my actual PC in a spare SSD, and same story.

I used these exact steps in Lubuntu 22.04 before and it worked just fine. Is it a known bug in the new 24.04 LTS?

UPDATE: In case its useful, here are a couple of screenshot comparisons from VirtualBox between Lubuntu 22.04.4 and Lubuntu 24.04 installation.

Lubuntu 22.04 (works):

Lubuntu 22.04 disk config

Lubuntu 22.04 installation overview

Lubuntu 24.04 (doesn't work):

Lubuntu 24.04 disk config

Lubuntu 24.04 installation overview

UPDATE 2: I tried selecting the erase whole drive option and encrypt from there, and that seems to be working. I tried both Kubuntu 24.04 and Lubuntu 24.04 in VirtualBox, and they both seem to be working as expected. Encrypting whole drive of course lacks the flexibility of manual partitioning.

system-installation

1 Answers

  1. Best Answer

    Comment #24 by Aaron Rainbolt (arraybolt3) on this bug report clarified it:

    It looks like you don't have a separate /boot partition being created? All Ubuntu flavors use Canonical's build of GRUB (naturally), and Canonical explicitly does not support /boot being located on an encrypted partition. It actually creates additional security risks to do so as Canonical doesn't test the code that handles encrypted /boot.

    Most likely what broke this is we changed from LUKS1 to LUKS2 in Lubuntu to increase security. I do not believe GRUB supports LUKS2. As encrypted /boot is not supported, and as there are security concerns when using LUKS1, I don't think we probably should fall back to LUKS1.

    If you're really determined to install with /boot on an encrypted partition despite the fact that this is dangerous, try running sudo nano /etc/calamares/modules/partition.conf, and change luksGeneration: luks2 to luksGeneration: luks1. Then try installing with one big encrypted partition again. Again, this is dangerous, and also it has a good chance of breaking if you use a keyboard layout other than US.

    Hope this is helpful!

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