GRUB fails to install to MSDOS label disk when PC booted in UEFI mode

[alexandra]

error

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.14.12 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 4.18.0-15.16~18.04.1-generic 4.18.20
Uname: Linux 4.18.0-15-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CasperVersion: 1.394
CurrentDesktop: ubuntu:GNOME
Date: Mon May 20 19:29:18 2019
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed boot=casper only-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210)
ProcEnviron:
 LANGUAGE=ru_RU.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=ru_RU.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[TJ (tj)]

This appears to be caused by the partitioning on the target install disk. In the UbiquityPartman.txt log-file it shows towards the end there are 3 primary and 4 logical partitions, which means the disk label is MSDOS not GPT.

Looking further there is no EFI System Partition on /dev/sda.

Therefore the problem here is that the Ubuntu installer was booted by the PC in UEFI mode. You need to change that by selecting Legacy/BIOS/CSM boot of the Ubuntu installer at boot-time.

If Ubuntu installer boots in BIOS mode this problem will not occur.