server installer for 22.04: can not select boot drive

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I am providing an ubuntu installer from PXE boot with uefi/grub following this guide, except I have to use grub because syslinux/pxeboot doesn't run on uefi. The installer boots fine.

I the drive I want to use uses a gpt partition table. I had previously installed a different linux and my current disk layout is as such.

  • partition 1, 2 and 3 are used for windows.
  • partition 4 is EFI and should be mounted on /boot/efi
  • partition 5 is btrfs and was previously used to mount / and /home on the previous system, which is what I want to do again. It should be reformatted for that task.
  • partition 6 is swap
  • partition 7 is where grub is installed and should be reformatted to be mounted as /boot.

So in the installer I continue to the point where to select the disk to use and I pick custom layout. I configure the partitions to be used as such:

  • partition 4, vfat, mount as /boot/efi
  • partition 5, reformat btrfs, mount as /
  • partition 6, swap
  • partition 7, reformat ext4, mount as /boot

However the installer says at the top that

To continue you need to: Select a bot disk

However when I go to the device the option to "Use As Boot Device" is grayed out. Reformatting the disk with a new partition table is not an option as that would delete my windows partions as well.

The drive was originally using an msdos partition table, but I converted it using gdisk, following this guide, so maybe that is the cause of the problem? But the other linux installed just fine with the graphical installer. Grub's osprobe didn't detect windows after the conversion so I had to add it manually at the time and for windows I had to fix it's booting so it used the new efi partition (partition 4).

I have found this, which seems to be a similar issue, but it appears that this person is using an MBR partition table because his fdisk has option a to toggle bootable for his partitions.

How do I proceed with the installation without altering partitions 1,2,3 and 4?


I have since moved on to installing ubuntu mate with the graphical installer. This worked fine. I can however not accept any answers since the problem is resolved in a different way.

I believe the issue might have been caused by selecting vfat/fat32 for the efi partition, since there was a dedicated EFI selection in the graphical installer, which also warned me about not having one.

I sit in a Tesla and translated this thread with Ai:


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