When booting, grub goes to the prompt (grub>, not grub rescue>). I need to type in:

set prefix=(hd0,gpt8)/boot/grub
insmod normal

To get the normal grub menu.

Every post I found so far was solved by doing grub-install and/or update-grub once you manage to boot your system.
I tried these but the problem persists.


I dual boot with windows 10 and pop-os (ubuntu-based). I have an acer laptop with boot mode set to UEFI and secure boot enabled.

My partitions look like this:

NAME            SIZE FSTYPE MOUNTPOINT UUID                                 LABEL    PARTUUID                             PARTTYPE
sda           238.5G                                                                                                      
├─sda1          529M ntfs              6272EE1672EDEF2B                     Recovery b593e2b8-992e-4d79-9074-d990ba21d10c de94bba4-06d1-4d40-a16a-bfd50179d6ac
├─sda2          100M vfat              64EE-A907                                     6ef6e12c-3858-4a83-a1dd-8297719bd477 c12a7328-f81f-11d2-ba4b-00a0c93ec93b
├─sda3           16M                                                                 1b6ba39a-e528-4cf9-b158-cd1a9312afc2 e3c9e316-0b5c-4db8-817d-f92df00215ae
├─sda4        117.2G ntfs              8E6008B56008A655                              c2f2d5bf-16a3-4e99-a6db-2385b36f3f46 ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
├─sda5         58.6G ntfs              F6D0CCD7D0CC9EED                     Storage  c10e8d39-26c3-4d3b-8548-0aa97816ba0b ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
├─sda6          477M swap              74da5edc-3b6c-4644-a151-6b93562c8fa4          408e91bd-c7e7-4ab8-a2ac-bb2bb7fde375 0657fd6d-a4ab-43c4-84e5-0933c84b4f4f
│ └─cryptswap 476.5M swap   [SWAP]     2d2336c7-64c1-4d53-8e99-f66f9b93bef5                                               
├─sda7          600M vfat   /boot/efi  7565-8082                                     a8c1ff00-3790-4ca0-a360-642e6f1859f0 c12a7328-f81f-11d2-ba4b-00a0c93ec93b
└─sda8           61G ext4   /          d40fe3bd-0749-4c29-9e9b-97a064a659dd          8a3b8567-c511-48cd-a3fa-776b556d17da 0fc63daf-8483-4772-8e79-3d69d8477de4
  • Partitions 1-4 were created by windows, the bootloader is on sda2.
  • Partition 5 is created by me to easily share files between windows/linux.
  • The remaining partitions were created by pop-os (after completing the windows installation), the pop-os bootloader is on sda7.

I installed grub as:

$ sudo apt install grub-efi
$ sudo grub-install --bootloader-id=grub
Installing for x86_64-efi platform.
Installation finished. No error reported.
$ sudo update-grub
Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/init-select.cfg'
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-5.4.0-7642-generic
Found initrd image: /boot/initrd.img-5.4.0-7642-generic
Found linux image: /boot/vmlinuz-5.4.0-7634-generic
Found initrd image: /boot/initrd.img-5.4.0-7634-generic
Found linux image: /boot/vmlinuz-5.4.0-7629-generic
Found initrd image: /boot/initrd.img-5.4.0-7629-generic
Found linux image: /boot/vmlinuz-5.4.0-7626-generic
Found initrd image: /boot/initrd.img-5.4.0-7626-generic
Found Windows Boot Manager on /dev/sda2@/efi/Microsoft/Boot/bootmgfw.efi
Adding boot menu entry for UEFI Firmware Settings

After which my /boot directory looks like this:

$ sudo tree -a /boot
├── config-5.4.0-7626-generic
├── config-5.4.0-7629-generic
├── config-5.4.0-7634-generic
├── config-5.4.0-7642-generic
├── efi
│   ├── c0cc91f7cdfcb9a597d9db525eb08842
│   ├── EFI
│   │   ├── BOOT
│   │   │   └── BOOTX64.EFI
│   │   ├── Linux
│   │   ├── grub
│   │   │   ├── grub.cfg
│   │   │   └── grubx64.efi
│   │   ├── Pop_OS-d40fe3bd-0749-4c29-9e9b-97a064a659dd
│   │   │   ├── cmdline
│   │   │   ├── initrd.img
│   │   │   ├── initrd.img-previous
│   │   │   ├── vmlinuz.efi
│   │   │   └── vmlinuz-previous.efi
│   │   └── systemd
│   │       └── systemd-bootx64.efi
│   ├── loader
│   │   ├── entries
│   │   │   ├── Pop_OS-current.conf
│   │   │   └── Pop_OS-oldkern.conf
│   │   ├── loader.conf
│   │   └── random-seed
│   └── System Volume Information
│       ├── AadRecoveryPasswordDelete
│       └── ClientRecoveryPasswordRotation
├── grub
│   ├── fonts
│   │   └── unicode.pf2
│   ├── grub.cfg
│   ├── grubenv
│   └── x86_64-efi
│       ├── acpi.mod
|       < files omitted ... > 
│       └── zstd.mod
├── initrd.img -> initrd.img-5.4.0-7642-generic
├── initrd.img-5.3.0-7642-generic
< files omitted ... > 
├── initrd.img.old -> initrd.img-5.4.0-7634-generic
├── System.map-5.4.0-7626-generic
< files omitted ... > 
├── vmlinuz -> vmlinuz-5.4.0-7642-generic
├── vmlinuz-5.4.0-7626-generic
< files omitted ... > 
└── vmlinuz.old -> vmlinuz-5.4.0-7634-generic

16 directories, 314 files

The files under /boot/efi/EFI/grub, /boot/efi/EFI/BOOT and /boot/grub are newly added by grub-install.

In addition, this looks fine to me:

$ cat /boot/efi/EFI/grub/grub.cfg 
search.fs_uuid d40fe3bd-0749-4c29-9e9b-97a064a659dd root hd0,gpt8 
set prefix=($root)'/boot/grub'
configfile $prefix/grub.cfg

After rebooting, i hit F2 and managed to add EFI/grub/grubx64 to the top of the boot order. enter image description here

After saving & exiting I land into the grub prompt.

Then, using the set command I see the following output (some entries omitted):

grub> set

I'm lost now, it seems that the correct bootloader was loaded (cmdpath=(hd0,gpt7)/EFI/pop), but the settings in EFI/grub/grub.cfg are completely ignored. Where is it getting these incorrect settings from?

After fixing prefix as decribed above, I get a fully functional grub menu with an entry for 1. pop-os, 2. pop-os fallback images, 3. windows and 4. the boot setup. I tried all options and they all work.

So I managed to boot into popOs, efibootmgr -v tells me this:

$ efibootmgr -v
BootCurrent: 0003
Timeout: 0 seconds
BootOrder: 0003,0001,0002,0000,2001,2002,2003
Boot0000* Windows Boot Manager     HD(2,GPT,6ef6e12c-3858-4a83-a1dd-8297719bd477,0x109000,0x32000)/File(\EFI\Microsoft\Boot\bootmgfw.efi)RC
Boot0001* systemd                  PciRoot(0x0)/Pci(0x17,0x0)/Sata(2,0,0)/HD(7,GPT,a8c1ff00-3790-4ca0-a360-642e6f1859f0,0x160d3000,0x12c000)/File(\EFI\systemd\systemd-bootx64.efi)A01 ..
Boot0002* HDD0: HFS256G39TND-N210A PciRoot(0x0)/Pci(0x17,0x0)/Sata(2,0,0)/HD(7,GPT,a8c1ff00-3790-4ca0-a360-642e6f1859f0,0x160d3000,0x12c000)RC
Boot0003* grub                     PciRoot(0x0)/Pci(0x17,0x0)/Sata(2,0,0)/HD(7,GPT,a8c1ff00-3790-4ca0-a360-642e6f1859f0,0x160d3000,0x12c000)/File(\EFI\grub\grubx64.efi)A01 ..
Boot0004* EFI USB Device           RC
Boot0005* EFI DVD/CDROM            RC
Boot0006* EFI Network              RC
Boot2001* EFI USB Device           RC
Boot2002* EFI DVD/CDROM            RC
Boot2003* EFI Network              RC

what I expect should happen

  1. I start grub, at (hd0,gpt7)/EFI/grub/grub.efi from the UEFI firmware.
  2. grub reads the config file at (hd0,gpt7)/EFI/grub/grub.cfg. This sets root to (hd0,gpt8) and prefix to (hd0,gpt8)/boot/grub.
  3. grub loads the configuration at (hd0,gpt8)/boot/grub/grub.cfg.
  4. grub presents me with a menu, I choose the OS I want to load and go on with my day.

what actually happens

  1. I start grub, at (hd0,gpt7)/EFI/grub/grub.efi from the UEFI firmware.
  2. grub does not read the config file at (hd0,gpt7)/EFI/grub/grub.cfg. Instead it sets root to (hd0,gpt7) and prefix to (hd0,gpt7)/boot/ubuntu.

    I manually fix the incorrect prefix as described above.
  3. grub loads the configuration at (hd0,gpt8)/boot/grub/grub.cfg.
  4. grub presents me with a menu, I choose the OS I want to load and go on with my day.

things I tried:

  • disabling secure boot (no difference)
  • re-running grub-install and upgrade-grub (no difference)
  • sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=grub --recheck --debug /dev/sda &> grub.log (no difference, output here)
  • You show two vfat partitions, are both set as ESP. Generally you can only have one as ESP, but entries for grub and maybe UEFI use UUIDs & GUIDS, so flag is more for where boot loader is installed. And then do you have an old UEFI grub entry in Windows's ESP that is failing to boot? Check that GUID/partUUID in UEFI boot entry matches partuuid. lsblk -o name,mountpoint,label,size,fstype,uuid,partuuid | egrep -v "^loop" and sudo efibootmgr -v
    – oldfred
    Commented Oct 18, 2020 at 13:56
  • Hi, thanks for your feedback. I don't really know what you mean by 'are both set at ESP', how should I check this? I Also put the output of the commands you gave in a gist (gist.github.com/SamDM/…). If I interpret the output correctly, the entries seem to match. Commented Oct 18, 2020 at 14:26
  • Also, on dev/sda I can't see any grub-related files. I believe all files on that partition are created by windows (file tree: gist.github.com/SamDM/…). Commented Oct 18, 2020 at 14:31
  • If you look close your "ubuntu" entry at 0007 uses GUID from sda2. Pop entry which shows as default uses sda7. With most Acer, you have to set "trust" on entry to have it work. Is Pop entry "trusted"? ubuntuforums.org/showthread.php?t=2297947 Many Acer also need UEFI update. askubuntu.com/questions/908854/… & askubuntu.com/questions/627416/… & askubuntu.com/questions/1217061/…
    – oldfred
    Commented Oct 18, 2020 at 16:19
  • Yep I am a bit puzzled by the Boot0007, which points to a non existing file on the filesystem. It may be a remnant of an old ubuntu install. And maybe I should try removing it. Although I doubt it would solve anything, it is worth trying. To answer your question, I have indeed added the EFI/pop/grubx64.efi entry to the trusted bootloaders in the Acer firmware settings. This is the file generated by grub-install. I'm pretty confident this pop entry is also the one that is booted up since cmdpath=(hd0,gpt7)/EFI/pop in the grub shell. Commented Oct 18, 2020 at 18:14

3 Answers 3


When grubx64.efi is generated by grub-mkimage, a default prefix value can be embedded into it.

In Debian, this is set to /EFI/debian when grub-mkimage is called by grub-install; in Ubuntu, the prefix will be /EFI/ubuntu respectively. This causes GRUB to first read a mini-configuration file located as /EFI/(debian|ubuntu)/grub.cfg, which typically contains only a few lines to redirect GRUB into wherever the /boot directory/filesystem is located, to read the real configuration file from there:

<any configuration lines required to cover complications like software RAID, disk encryption or LVM>
search.fs_uuid <UUID of the filesystem that contains /boot>
set prefix=($root)'/boot/grub' # or just ($root)/grub if /boot is a separate filesystem 
configfile $prefix/grub.cfg

If you are using Pop!OS's GRUB package, it might have a similar left-over "ubuntuism" in its grub-install/grub-mkimage defaults, if Pop's packagers have not paid enough attention. And since Pop's default UEFI bootloader seems to be gummiboot rather than GRUB, such a bug might have gone unnoticed.

If you have installed the grub-efi-amd64-signed package for Secure Boot compatibility, your original /boot/efi/EFI/pop/grubx64.efi may in fact be different from /boot/grub/x86_64-efi/grub.efi, as the former has gone through the Secure Boot signing process and usually has essentially all the GRUB modules built-in.

Perhaps the Pop!OS developers have used Ubuntu's grub-efi-amd64-signed package as-is, without applying the changes they've made to the non-SecureBoot-signed version?


When grub-install is used with the --uefi-secure-boot option, or if Secure Boot is detected, then instead of using grub-mkimage to build an optimized grubx64.efi for the system GRUB is being installed to, it uses a pre-compiled and Secure Boot-signed /usr/lib/grub/x86_64-efi-signed/grubx64.efi.signed.

At least in Debian, this is built using reproducible build techniques, so with the corresponding version of the source package and a detached Secure Boot signature file, anyone can compile it for themselves and verify that the result will be absolutely identical to the pre-built version. Getting that part working right was apparently the major reason why it took a while to get Secure Boot support into Debian.

  • 1
    Hi, your answer led me to a solution! You're right that searching for EFI/ubuntu/grub.cfg is hard-baked into the binary. So here is what I did: sudo mv /boot/efi/EFI/grub /boot/efi/EFI/ubuntu. Then I did a reboot and I land right into a fully functional grub menu with options for popOs (on gpt7 & 8) windows (on gpt 2 and 4) and UEFI firmware settings. It all works perfectly. It does look like a an oversight from popOs developers. Because by default grub-install will put the (small) config file in /boot/efi/EFI/pop. Commented Oct 26, 2020 at 21:55
  • Thanks for the pointers, If you could include my workaround in your answer I'll accept it as 'solved'. If you don't care about SO reputation I'll post my own answer describing the workaround. Commented Oct 26, 2020 at 21:58
  • Now that I know what to look for, I also found the following workaround (haven't tested it myself): sudo cp /boot/grub/x86_64-efi/grub.efi /boot/efi/EFI/pop/grubx64.efi. See github.com/pop-os/pop/issues/1007 Commented Oct 26, 2020 at 22:17
  • 1
    @SamDeMeyer Feel free to post your own answer. If copying /boot/grub/x86_64-efi/grub.efi to /boot/efi/EFI/pop/grubx64.efi helps, it might be that the actual GRUB package of Pop!OS is now fixed, but the fix may have not been propagated to the grub-efi-amd64-signed package (which provides another copy of grubx64.efi that's been signed for Secure Boot).
    – telcoM
    Commented Oct 26, 2020 at 23:28

The exact reason for this problem is not yet entirely clear, but it may have something to do with incorrectly configured grub packages by the popOs maintainers.

I managed to work around it by copying the grub files created by grub-install to /boot/efi/EFI/ubuntu. If you're on popOs and did grub-install without any options, then the following should work:

sudo mv /boot/efi/EFI/pop /boot/efi/EFI/ubuntu

An alternative workaround, which I haven't tested is:

sudo cp /boot/grub/x86_64-efi/grub.efi /boot/efi/EFI/pop/grubx64.efi

For more info, see the bug report.


Quoted from Sam De Meyer Answer,

An alternative workaround, which I haven't tested is:

sudo cp /boot/grub/x86_64-efi/grub.efi /boot/efi/EFI/pop/grubx64.efi

Moving grub.efi from /boot/grub/x86_64-efi to the efi partition (which one on my os is on /boot/efi/EFI/neon/grubx64.efi) makes the GRUB's theme could not be used even though I have applied it in /etc/default/grub with GRUB_THEME configuration. The default blue grub theme is used instead.

The solution for me to fix this issue with keeping my theme works is just to copy the /boot/efi/EFI/neon/grub.cfg to /boot/efi/EFI/ubuntu/grub.cfg

sudo cp /boot/efi/EFI/neon/grub.cfg /boot/efi/EFI/ubuntu/grub.cfg

Before doing that, you should run sudo grub-install first.

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