Update-grub missing one OS

johnrcox · July 7, 2026, 1:25am

Ubuntu Support Template

Ubuntu Version:
26.04

Desktop Environment (if applicable):
GNOME

Problem Description:
grub does not show one system.

My system has 3 different versions

of linux installed/

Screen goes black

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What I’ve Tried:
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johnrcox · July 7, 2026, 1:35am

Sorry, I screwed that up.

I am running Ubuntu 26.04 LTS. I just installed it. I have 2 other OSes on my system: Linux Mint and openSUSE Tumbleweed.

When I boot up, Grub shows Ubuntu, 4 Memtests, Linux Mint, but not openSUSE.

I have tried update-grub with no changes.

os-prober shows the following:

root@bopper:~# os-prober
/dev/sda1:Linux Mint 22.3 Zena (22.3):LinuxMint:linux
/dev/sdb1:openSUSE Tumbleweed:openSUSE:linux
root@bopper:~#

Any idea how to make it work?

guiverc · July 7, 2026, 1:49am

Your issue is likely related not to OS, but the file-system used.

OpenSuSE can default to btrfs which can be scanned by Ubuntu/Debian grub (I’ve used it myself), but it is more involved.

What file-system have you elected to use with OpenSuSE ? as that is likely your complication.

( Encryption and other factors can make dual booting with grub more complex; so specifics matter; but your mention of OpenSuSE makes me think of btrfs as one example )

peterwhite23 · July 7, 2026, 2:53am

It may also be of interest what your grub menu entries look like. The way you describe it, @johnrcox, there isn’t even a menu entry for openSUSE, so something must be going wrong when creating (update-grub) it. As I’ve learnt recently, you need to be careful with update-grub, when TPM-backed full disk encryption (TPM/FDE) is enabled, so DO NOT RUN THIS, IF YOU HAVE TPM/FDE enabled

sudo update-grub

Usually the output of that command should already tell you, if the menu entry for openSUSE is being created. Otherwise, a look inside /boot/grub/grub.cfg should provide further clues.

(edited to put code where code belongs )

Please put all log and other console/terminal output in pre-formatted code blocks (open a new line and click the </> icon in the editor first, then paste into the new element), ideally wrapped in a “Hide Details” element, if it’s more than just a few lines. See items 4 and 5 in the Posting Guide.

Optional helper script

If you are so inclined, I took it upon myself to provide a little helper script for that.

johnrcox · July 7, 2026, 4:17am

My openSuse system is using ext4 filesystems.

I don’t see any error messages using “update-grub” Do you think it’s just a bug?

rubi1200 · July 7, 2026, 4:23am

Please boot using either a live USB or from within the install and choose the option for the summary report.

Post the pastebin back here.

tea-for-one · July 7, 2026, 12:18pm

No, I don’t think that it’s a bug because Linux Mint is found by sudo update-grub

Therefore one would suspect that the grub configuration in openSUSE Tumbleweed is different.
A quick internet search found that a modified grub is used byTumbleweed

peterwhite23 · July 7, 2026, 1:43pm

If that’s the case, then @johnrcox should be able to chainload it. Somehow I always assumed that update-grub would simply find the other Linux boot loaders and just create chainload menu entries entries, but, since I don’t multi-boot different OS’s on bare metal and use VM’s when I want to run some other OS, I have never seen it in action, and it turns out, I was mistaken.

Found this on the Mint forums, while researching what update-grub actually does:

You can do what you want by chainloading the secondary OS’s grub from your main OS grub using the file /etc/grub.d/40_custom.
Here’s an example of one I used when dual booting with Arcolinux several months ago where I could not get Arcolinux to boot directly from the Mint grub for some reason I never figured out.
#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
#
# The 6 lines below are to chainload grub for Arcolinux
#
menuentry 'ArcoLinux' {
insmod part_gpt
insmod fat
search --no-floppy --fs-uuid --set=root 73BF-188B
chainloader /EFI/ArcoLinux/grubx64.efi
}
#
menuentry "Reboot" {
	reboot
}
#
menuentry "Poweroff" {
	halt
}

Looks like that’s what one wants update-grub to do automatically for all other boot loaders, but that’s just me being puzzled, perhaps.

Dennis_N · July 7, 2026, 2:15pm

If your system is UEFI, you could install refind from the Ubuntu repository. On restart, you should get refind’s menu instead of a grub menu (since refind puts itself first in UEFI boot order). If it works, OpenSuse options should be shown.

oldfred · July 7, 2026, 2:54pm

First thing I do is turn off os–prober. I have lots of installs, often only want a few as others may be obsolete. Also os-prober has to scan every partition. Recommended to turn off as possible security issue. And every kernel update runs os-prober scan of every partition. On my system takes a bit of time.

I have used rEFInd for emergency boot from very old, too small for anything else flash drive.
Many have recommended & use rEFInd.feature

In my 40_custom I have used chainload to Windows, configfile to other grub menus, and full boot stanza. One nice thing about Ubuntu is that it has a link to most current kernel so boot stanza to Ubuntu can be to link. Otherwise boot stanza has to be updated with every kernel update.

One configfile example:

Other file systems, configurations may need grub’s insmod commands to add modules.

You can copy a boot stanza from another install into 40_custom. Most encrypted installs have an unencrypted /boot partition. Or you can configfile into ESP’s grub which is a configfile. If other install LVM and booting from non-lvm, you need to add LVM drivers into boot install.

Do you have UEFI boot entries in ESP for each install?
And if on different drives, ESP on same drive as install?

Boot-Repair report will show many details of your install. Then we can make specific recommendations. Boot-Repair is implementing a change from Ubuntu pastebin site as now closed.

avb66 · July 7, 2026, 6:28pm

Run as root

NOW=$(date +@%s)
update-grub
journalctl --system --no-pager --full --since $NOW

and post the output.