I've installed a new motherboard into my server (SuperMicro X9DRi-F) and I'm trying to install a fresh copy of Debian 10. However, when it tries to install GRUB it fails:

Unable to install GRUB in dummy
Executing 'grub-install dummy' failed.
This is a fatal error.

I'm making sure to boot the installer (USB drive) in UEFI mode because I'm entering the BIOS and forcing it to boot (which correctly displays "UEFI: Sandisk").

I can't cut and paste the /var/log/syslog message but here is basically what it says:

Installing grub on 'dummy'
grub-install does not support --no-floppy
Running chroot /target grub-install  --force "dummy"
Installing for x86_64-efi platform.
grub-install: warning: Cannot read EFI Boot* variables.
grub-install: warning: read_file: could not read from file: Input/output error.
grub-install: warning: vars_get_variable: read_file(...) failed: Input/output error.

I've searched and I see others with this problem but it's not clear how anybody has solved it?

Can anybody help me out?

  • Try posting a debian bug on this (and add a link to it here), this isn't something familiar to me -- and I've added UEFI support into ALT Linux. I'd probably try chrooting into the system being installed at that very stage and running grub-install --recheck -v. Maybe something here helps: rodsbooks.com/efi-bootloaders – Michael Shigorin Sep 13 '19 at 8:33
  • PS: does /sys/firmware/efi/ directory exist in chroot with system being installed at that stage? Maybe /sys is just not mounted there, although that would be so silly... – Michael Shigorin Sep 13 '19 at 8:35

had same problem during re-installation of grub on my system. My solution (chrooted into with debian live system):

~ # mount /dev/sdX /target
~ # mount -o rbind /dev /target/dev
~ # mount -t proc proc /target/proc
~ # mount -t sysfs sys /target/sys
~ # mount -t efivarfs efivarfs /target/sys/firmware/efi/efivars # added that line (in difference to all other manuals found on the internet..)
~ # chroot /target/
~ # grub-install
~ # update-grub
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