unattended usb installation fine, pve-iso-2-pxe converted failing at bootloader stage

[tru]

Hello,

I have sucessfully automated the proxmox installation with:

wget https://enterprise.proxmox.com/iso/proxmox-ve_8.2-2.iso
cat <<EOF1> fr-nvme-zfs.toml
[global]
keyboard = "fr"
country = "fr"
fqdn = "pveauto.testinstall"
mailto = "tru@pasteur.fr"
timezone = "Europe/Paris"
root_password = "changemenow"

[network]
source = "from-dhcp"

[disk-setup]
filesystem = "zfs"
zfs.raid = "raid0"
zfs.hdsize = 150
disk_list = ["nvme0n1"]
EOF1

proxmox-auto-install-assistant prepare-iso proxmox-ve_8.2-2.iso --fetch-from iso --answer-file fr-nvme-zfs.toml
sudo dd if=proxmox-ve_8.2-2-auto-from-iso.iso of=/dev/sdxxxx bs=8M status=progress

But when I convert the `proxmox-ve_8.2-2-auto-from-iso.iso` into linux26 and initrd and PXE boot the same machine, the installation starts fine but fails at the last stage.

#!ipxe

imgfree
set opts "vga=791 video=vesafb:ywrap,mtrr ramdisk_size=16777216 rw quiet initrd=initrd proxmox-start-auto-installer splash=silent proxdebug"
echo ${opts}
initrd http://a.b.c.d/pub/proxmox/isos-url/pxeboot/initrd
kernel http://a.b.c.d/pub/proxmox/isos-url/pxeboot/linux26 ${opts}
boot || shell

logs:

2024-10-21 17:16:51.171 INFO: # umount /rpool/ROOT/pve-1/tmp/pkg
2024-10-21 17:16:51.176 INFO:
2024-10-21 17:16:51.176 INFO:
2024-10-21 17:16:51.176 INFO: # umount /rpool/ROOT/pve-1/tmp
2024-10-21 17:16:51.181 INFO:
2024-10-21 17:16:51.181 INFO:
2024-10-21 17:16:51.181 INFO: # umount /rpool/ROOT/pve-1/proc
2024-10-21 17:16:51.186 INFO:
2024-10-21 17:16:51.186 INFO:
2024-10-21 17:16:51.187 INFO: # umount /rpool/ROOT/pve-1/sys/firmware/efi/efivars
2024-10-21 17:16:51.192 INFO:
2024-10-21 17:16:51.192 INFO:
2024-10-21 17:16:51.192 INFO: # umount /rpool/ROOT/pve-1/sys
2024-10-21 17:16:51.197 INFO:
2024-10-21 17:16:51.197 INFO:
2024-10-21 17:16:51.197 INFO: # zfs umount -a
2024-10-21 17:16:51.404 INFO:
2024-10-21 17:16:51.404 INFO:
2024-10-21 17:16:51.404 INFO: # zfs set sync=standard rpool
2024-10-21 17:16:51.424 INFO:
2024-10-21 17:16:51.424 INFO:
2024-10-21 17:16:51.424 INFO: # zfs set mountpoint=/ rpool/ROOT/pve-1
2024-10-21 17:16:51.454 INFO:
2024-10-21 17:16:51.455 INFO:
2024-10-21 17:16:51.455 INFO: # zfs set mountpoint=/var/lib/vz rpool/var-lib-vz
2024-10-21 17:16:51.478 INFO:
2024-10-21 17:16:51.479 INFO:
2024-10-21 17:16:51.479 INFO: # zpool set bootfs=rpool/ROOT/pve-1 rpool
2024-10-21 17:16:51.495 INFO:
2024-10-21 17:16:51.495 INFO:
2024-10-21 17:16:51.496 INFO: # zpool export rpool
2024-10-21 17:16:51.627 INFO:
2024-10-21 17:16:51.627 INFO:
2024-10-21 17:16:51.629 ERROR: installation failed: bootloader setup errors:
- unable to update boot loader config
2024-10-21 17:16:51.629 INFO: finished: err, bootloader setup errors:
- unable to update boot loader config