Install Kubuntu without EFI bootloader

If you have, i.g., another linux distro, such as KDE-Neon, and you want add Kubuntu as secondary SO, without changing your EFI, you do this way:

  • in Kubuntu (usb iso) menu -> try Kubuntu
  • in a terminal (once logged in): ubiquity -b
  • this will open the graphical installation tool letting you install Kubuntu without modifying existing EFI
  • don’t worry for the warnings (“the system could not start”)
  • after rebooting, in KDE-Neon do update-grub

If you get, with update-grub, an error such this:


Warning: os-prober will not be executed to detect other bootable partitions.
Systems on them will not be added to the GRUB boot configuration.

You can solve adding or uncommenting this line in /etc/default/grub

GRUB_DISABLE_OS_PROBER=false


boot useful tips

  1. It is not necessary to start booting with EFI if you have GPT partitions (you could choose to have legacy boot with GPT partitions).
  2. It is not necessary that EFI partition be at the start of a disk: it could be in every place, provided that it has a) boot (esp) flags, and b) at least 110mb of space.

System not starting after upgrading to Ubuntu 22.04

After upgrading Ubuntu from 20.04 to 22.04 it can happen that you cannot start the desktop: emergency mode.

In some case it could be happened that fstab was modified and the efi partition is set with a wrong UUID. Therefore you can try to change, in your fstab file, the efi UUID (i.g. copying it from a working installation).