Cannot install Kubuntu as a dual-boot in UEFI mode

[Mika Mäki]

Attempting to install Kubuntu 22.04.1 from a UEFI-booted USB drive to a GPT-formatted SSD with an existing Windows installation results in the error "Executing 'grub-install /dev/sda' failed. This is a fatal error". The USB drive is booted in UEFI mode with Secure Boot enabled. The target partitions for root, swap and boot have been specified manually for a LUKS-encrypted installation alongside an existing unencrypted Windows installation, but the target for the bootloader has been left as the default (/dev/sda). The swap and ext4-formatted root partition on an LVM inside a LUKS container, and the boot partition is a normal ext4-formatted partition. The existing EFI system partition has been selected to be used. Online sources seem to indicate that the setting for the bootloader target should not matter in the UEFI mode, as the boot configuration should be automatically written to the EFI system partition instead. However, it seems that the installer might not somehow recognize that Kubuntu is being installed in UEFI mode.

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: ubiquity 22.04.17 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 5.15.0-43.46-generic 5.15.39
Uname: Linux 5.15.0-43-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.1
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.470
CurrentDesktop: KDE
Date: Fri Sep 9 19:10:50 2022
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/kubuntu.seed maybe-ubiquity quiet splash ---
LiveMediaBuild: Kubuntu 22.04.1 LTS "Jammy Jellyfish" - Release amd64 (20220809.1)
RebootRequiredPkgs: Error: path contained symlinks.
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)