Failed to install grub on a fresh install with custom partition selection

[Heiko Voigt]

When starting a fresh install for Ubuntu 18.04.1 I encountered this bug.

The system has an SSD with Windows 10 on other partitions and the Ubuntu system should go on there while the /home partition has its own disk. I selected the SSD as the target to install grub.

I started the install from an USB stick. While the installer was copying files it told me at one point that grub can not be installed on "/target" and the installation stopped.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.14.6 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 4.15.0-29.31-generic 4.15.18
Uname: Linux 4.15.0-29-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
CasperVersion: 1.394
CurrentDesktop: ubuntu:GNOME
Date: Wed Oct 17 11:49:13 2018
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed boot=casper only-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
ProcEnviron:
 LANGUAGE=de_DE.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Heiko Voigt (hvoigt)]

It seems to be a secure boot / UEFI issue. Retrying with the same bootentry and a minimal install also failed. I briefly saw something about grub not being able to write somewhere in the install console.

Unfortunately I am not able to copy the text here, because the error message box of the installer went above that. It would be nice if one could investigate the output of the installer a bit more. It seems it is not attached automatically here. Also after closing that message box the installer console immediately dissapears, not very helpful to produce a proper report.

When I selected a different boot entry for my USB-Stick (one without UEFI in the name) I was able to install ubuntu without any problems.