grub-installer crashes when installing alongside Windows

[Max Kaehn]

Windows 10 wouldn't let me shrink its partition far enough, so I had to reinstall it from scratch. I reformatted another partition on the SSD to ext4, then ran the 18.04.1 installer and it crashed when trying to install the boot loader.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.14.6
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 Sep 5 00:33:59 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=en_US.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Max Kaehn (slothman)]

Bug #1790803 is a duplicate that contains another set of logs from when I reproduced the problem.

[Max Kaehn (slothman)]

I was able to work around this by manually copying .efi files into /boot/efi/EFI/ubuntu and setting up a grub.cfg in there.