grub fails on fresh Ubuntu 21.04 installation

[Miikka-Markus Alhonen]

I did a fresh Ubuntu 21.04 installation from a USB drive on a machine which already had Windows 10. I selected default settings for dual-boot, did not connect to Wifi since I didn't have time to wait for downloads, and checked 3rd party software. Everything went fine until it was time to set up grub, at which point I got a fatal error saying grub installation failed on /dev/sda. The installation program launched desktop mode, so that I could investigate the problem. I downloaded boot-repair and launched it but it failed, since the installation program was still running. Next I shut down the computer and was surprised to notice that the hard drive did actually boot grub, from where I was able to select Ubuntu. Though the system had started, I decided to run boot-repair again just to make sure nothing's missing. Boot-repair suggested some commands (including apt install -fy) that I copy-pasted to term, and as a result I lost access to Wifi and could not mount the USB drive anymore - apparently it had removed network-manager plus other important packages and had not reinstalled them. At this point, booting from the hard drive had stopped working, as I was only presented with a "grub rescue" prompt, so I booted a live system from the Ubuntu installation flash drive, downloaded boot-repair and ran it again. Boot-repair claimed to have fixed something but even after that, I only got a grub rescue prompt. Then I rebooted from the Ubuntu USB again, and selected reinstallation without removing user files. This time I connected to Wifi but unchecked updates during installation. Everything progressed normally until it was again time to set up grub, and the system gave me the same fatal error as in the beginning. I'm still looking for a way to make everything work.

The machine is an older HP Pavilion g series laptop with BIOS (no UEFI), Windows is on /dev/sda1 with around 250 GB of space and the partition I tried Ubuntu on is at the end of the hard drive with around 450 GB of space. There are a couple of smaller partitions in between (Windows rescue etc.).

ProblemType: Bug
DistroRelease: Ubuntu 21.04
Package: ubiquity 21.04.19
ProcVersionSignature: Ubuntu 5.11.0-16.17-generic 5.11.12
Uname: Linux 5.11.0-16-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu65
Architecture: amd64
CasperMD5CheckMismatches: ./pool/restricted/n/nvidia-graphics-drivers-390/libnvidia-gl-390_390.141-0ubuntu2_amd64.deb ./pool/restricted/n/nvidia-graphics-drivers-460/libnvidia-gl-460_460.67-0ubuntu1_amd64.deb
CasperMD5CheckResult: fail
CasperVersion: 1.461
CurrentDesktop: ubuntu:GNOME
Date: Tue Jul 20 16:59:52 2021
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed maybe-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 21.04 "Hirsute Hippo" - Release amd64 (20210420)
ProcEnviron:
 LANGUAGE=fi_FI.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=fi_FI.UTF-8
 LC_NUMERIC=C.UTF-8
RebootRequiredPkgs:
 linux-image-5.11.0-16-generic
 linux-base
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Nathan J Lewicki (xyta777)]

Did you get a solve for this? I'm in the exact same boat as you except trying to install on an older dell. W10, several partitions, GRUB errors, installing from USB