While running Ubuntu 19.10 64 bit. Was offered an upgrade to Ubuntu 20.04. Offer accepted. Shortly after the upgrade started it stopped with the message

EFI System Partition (ESP) not usable

Your EFI System Partition (ESP) is not mounted at /boot/efi. Please ensure that it is properly configured and try again.

I don't care if the EFI or ESP is not usable. I don't want a bootloader installed. This is a multi boot system with 5 or 6 other Linux installations and I am using rEFind to boot the computer.

Don't want. Don't need. We do this the way I want it done or we format the partition and install something else.

How can I upgrade without installing a bootloader?

  • If you want a new install, you can choose not to install grub. This launches the installer program (Ubiquity) with an option (-b) to not install a boot loader from live installer in live mode: In the Terminal window, type ubiquity -b. Grub install will not only create new /EFI/ubuntu but overwrite /EFI/Boot/bootx64.efi with a copy of shimx64.efi. Your rEFInd uses /EFI/Boot/bootx64.efi. So always best to have good backup of your ESP, which most do not do. And in UEFI mode choices do not work. bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1396379 – oldfred May 24 at 14:46

If you expicitly want to avoid the standard process the updater is made for, just do a sudo sed -i 's/eoan/focal/g' /etc/apt/sources.list, followed by sudo apt update && sudo apt full-upgrade. Be prepared for questions from apt during the process and decisions you have to make yourself, instead of the Ubuntu installer doing that for you.

You also have to make sure that any ppas you have have to be manually lifted to Focal, or kept at Eoan, or deleted, after the upgrade went through.

If you are Power User enough to use rEFInd with different distros, it shouldn't be too difficult. Everyone else, you are advised to stick to the Ubuntu installer.

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