TLDR: the kernel command line is missing the rootflags=subvol=@

If you currently (KaOS 2018.10 ISO) install KaOS with btrfs, you will get an error sounding like this:

ERROR : Root device mounted successfully, but /sbin/init does not exist.

The problem is that Calamares (the installer) creates subvolumes. One subvolume for the root directory / named @ and one subvolume for the user directory /home named @home. Doing it like this is good pratice and similarly done by other distros too. The problem is that Calamares sets the right UUID for the root disk to boot, but forgets to tell that the root is now a subvolume.

Solution for UEFI & systemd-boot

Conditions:

  • UEFI is used to boot up the system
  • the hard drive was formated using GPT
  • systemd-boot is used as boot loader (default for UEFI)

You need to add rootflags=subvol=@ to your kernel command line options in the loader entries.

If you're still in the live environment you're good, if not please boot again from the Live-ISO to access the live environment.

Browse to /boot/loader/entries/ of the FAT32 partition you installed to (not the one of the Live-ISO!). There you will find the KaOS.conf and KaOS-fallback.conf. Open the KaOS.conf with an editor of your choice (you will need sudo rights) and edit the 6th line and add rootflags=subvol=@. It should look something like this:

options quiet systemd.show_status=0 root=UUID=95fb00c2-e5e3-68b4-7f07-5bdd5bf99f1b rootflags=subvol=@ rw

Save the changes. Repeat the same for KaOS-fallback.conf.

After a reboot you should see the systemd-boot boot menu and then KaOS should just start as expected.

Grub, BIOS, ...

Sorry, I have no tested solution for usage with Grub or non-UEFI systems as I don't use either.

The problem has been reported to the KaOS developer and is known. Hopefully in future Live-ISOs the problem will be solved.