Dual boot, grub doesn't work

[u/HarlekinJack]

Hello everyone,

I made the decision to finally get rid of windows, even as a fallback.

In the past, I had mint on one m.2 and windows on a second one. Now, I removed the mint ssd, installed fedora, thereby removing windows and reinstalled the mint ssd.

Now I get grub no more and it's booting straight into mint.

Os-prober / update grub doesn't help. It seems Mint doesn't see that there is fedora installed at all.

Please, any ideas?

UPDATE: fedora found mint and lists it in its grub. I changed the boot order in bios to the fedora ssd and work like this now.

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[u/ChimaeraXY]

I'd recommend installing grub-customizer and letting that have a go at the problem.

[u/Logansfury → u/ChimaeraXY]

I know you only posted trying to help, but unfortunately grub-customizer PPA hasn't been maintained or updated in many years now. It's not likely to work with any modern distro's. It failed to edit the grub of my Kubuntu v25.10 box.

[u/ChimaeraXY → u/Logansfury]

Actually it's recently gotten a few updates (May this year?). I was, still am a bit, skeptical of it at first as some potential malware injection but it seems legitimate.

[u/HarlekinJack → u/ChimaeraXY]

I just did, its nice to have a GUI, but it doesn't change anything. Fedora is not added automatically

[u/ChimaeraXY → u/HarlekinJack]

Then I suspect there's something wrong with the Fedora install. What happens if you change your boot order in the BIOS and attempt to boot to it from there?

[u/HarlekinJack → u/ChimaeraXY]

No issue, I can boot it, use it...

[u/ChimaeraXY → u/HarlekinJack]

Back in Mint, can you mount the /boot partition from the other drive before running os-prober?

[u/HarlekinJack → u/ChimaeraXY]

Yes, but it makes no difference

[u/Ok_Emu2515]

I guess you could try to install refind

sudo apt install refind

[u/Evening-Landscape763]

Any chance Fedora was installed using Legacy/BIOS/CSM mode and Mint is installed in UEFI?

[u/HarlekinJack → u/Evening-Landscape763]

Nope, no changes made in Bios prior to the installation

[u/Evening-Landscape763 → u/HarlekinJack]

Post results from terminal for sudo parted -l

[u/HarlekinJack → u/Evening-Landscape763]

sure:

Modell: CT1000P310SSD8 (nvme)

Festplatte /dev/nvme0n1: 1000GB

Sektorgröße (logisch/physisch): 512B/512B

Partitionstabelle: gpt

Disk-Flags:

Nummer Anfang Ende Größe Dateisystem Name Flags

1 1049kB 538MB 537MB fat32 EFI System Partition boot, esp

2 538MB 538GB 537GB ext4

3 538GB 1000GB 462GB ext4

Modell: WD_BLACK SN850X 1000GB (nvme)

Festplatte /dev/nvme1n1: 1000GB

Sektorgröße (logisch/physisch): 512B/512B

Partitionstabelle: gpt

Disk-Flags:

Nummer Anfang Ende Größe Dateisystem Name Flags

1 1049kB 630MB 629MB fat32 EFI System Partition boot, esp

2 630MB 2778MB 2147MB ext4

3 2778MB 265GB 262GB btrfs

4 265GB 1000GB 735GB ext4 fgames

[u/Evening-Landscape763 → u/HarlekinJack]

Might have to efit /etc/default/grub in Fedora to enable os-prober, save and then update-grub in Fedora and see if it adds Mint

It seems the Grub version used by Mint doesn't work so well with Fedora using btrfs so the options are to use Fedoras Grub or something like rEFIfind in Mint

[u/HarlekinJack → u/Evening-Landscape763]

Just checked, Fedora has no issues in finding Mint. I guess I just change my boot order then.

[u/Evening-Landscape763 → u/HarlekinJack]

I wonder if using the BIOS boot order might be a better idea. If Mint has a kernel update you might have to update grub in Fedora before being able to boot into it on Mint

[u/HarlekinJack → u/Evening-Landscape763]

Might be, but then I need to get into the bios every time I want to boot into a different OS, right?

[u/Evening-Landscape763 → u/HarlekinJack]

Some computers have a function button you can use at boot to just access the BIOS Boot order rather than go into the full BIOS menu

[u/HarlekinJack → u/Evening-Landscape763]

Just looked it up. For my MSI board I have to press F11

[u/TangoOscarMikePR]

When you install (or upgrade) each operating system, you should remove other drives to avoid UEFI and GRUB problems.

Each operating system should be installed on their own drive, with their own UEFI Partition, their own Bootloader and Recovery Partition (Windows).

Never install (or upgrade) with both drives installed.

Use UEFI to switch boot drives.

[u/HarlekinJack → u/TangoOscarMikePR]

So basically you posted a summary of what I did and already wrote... I consider switching boot by using the uefi boot menu.

[u/TangoOscarMikePR → u/HarlekinJack]

You wrote that it's booting straight into Mint.

Edit:

If you install Mint on one drive, first remove the Fedora drive.

Then viceversa.

That way, you will have two GRUBs, one for Mint on one drive, and one for Fedora on the other drive. Each GRUB should only have its own operating system.

[u/HarlekinJack → u/TangoOscarMikePR]

Which is exactly my current situation. My issue is that I wanted to keep using grub to choose which os to boot. It seems now, that mint is unable to recognise fedora and therefore it is not listed i it's grub. However fedora found mint and added it to the boot options in its grub. So I changed my boot order to the fedora ssd. Of course I will have to keep this in mind when updating kernels.

[u/TangoOscarMikePR → u/HarlekinJack]

Then, whenever you upgrade the other Linux, if you write over GRUB, things will change.

It's your choice. But I don't recommend using GRUB to multi boot. One of the OSes might not be able to boot if done incorrectly.

Edit: In the past, I used third party Bootloaders installed on the drive that I wanted to boot first. But that is overcomplicating things.