SOLVED GRUB fatal error during install on RAID

Question

I'm trying to install elementary OS on raid0. My ESP, of course, is not part of the raid, but rather a separate partition near the beginning of one of the disks. I boot into the live ISO, download mdadm, then assemble my raid (raid0 striped across four nvmes). The install goes great and system files get downloaded and copied onto the raid just fine. However, things take a bad turn when grub tries to install the bootloader on ESP. Here is output from the install journal. As you might guess, boot partition is on /dev/nvme1n1p1 and root is on /dev/md125.

Jun 14 00:14:29 elementary grub-installer: info: grub-install does not support --no-floppy
Jun 14 00:14:29 elementary grub-installer: info: Running chroot /target grub-install  --force "/dev/nvme1n1p1"
Jun 14 00:14:29 elementary grub-installer: Installing for x86_64-efi platform.
Jun 14 00:14:30 elementary grub-installer: grub-install: error: disk `md125' not found.
Jun 14 00:14:30 elementary grub-installer: error: Running 'grub-install  --force "/dev/nvme1n1p1"' failed.
Jun 14 00:14:32 elementary nm-applet[27236]: gtk_widget_destroy: assertion 'GTK_IS_WIDGET (widget)' failed
Jun 14 00:14:32 elementary nm-applet[27236]: gtk_widget_destroy: assertion 'GTK_IS_WIDGET (widget)' failed
Jun 14 00:14:32 elementary nm-applet[27236]: Can't set a parent on widget which has a parent
Jun 14 00:14:43 elementary ubiquity[29013]: Reverting lockdown of the desktop environment.
Jun 14 00:14:43 elementary activate-dmraid: No Serial ATA RAID disks detected```

Answer 1

I got it to work... I must have done something incorrect when I installed grub the first time. After much internet searching, I found someone who had done something similar and I partially followed their instructions https://gist.github.com/umpirsky/6ee1f870e759815333c8

Answer 2

A quick update: I've reinstalled Elementary OS, and made it a bit farther. This time I did the following:

• booted into the live ISO,
• installed mdadm and assembled the raid where root will reside,
• successfully ran the installer from commandline: ubiquity -b (using the -b switch runs the installer, but will not install the bootloader, which is where I was encountering errors before)
• copied resolv.conf from live ISO to the corresponding location on the new install so I can download additional packages from the internet once in chroot environment
• chroot into the new install
• installed mdadm and grub-efi-amd64 packages in the new chroot environment
• ran grub-update and grub-install
• rebooted

Now I at least get the grub prompt. I haven't had time to work through grub prompt to set root and boot directories yet. Also, I am much more familiar with systemd-boot than grub, but would like to work through this issue with grub. So I'm looking for guidance on what I might have done wrong and why I'm booting to the grub prompt, and how I might adjust the grub install so that I can boot directly into the grub menu.