After installing Ubuntu 20.14 Windows 10 disappeared from Grub

21

Is that when you boot in legacy mode?

I was just going to try and explain this

I changed “Boot option filter UEFI + Legacy” to Legacy only and started again. This time Windows 10 was back again and ran well, but there was only 1 Ubuntu option in the Grub menu and that was Ubuntu 18.04. Now 22.04 (that ran perfectly) has disappeared,

What I was thinking was, you probably have 2 grubs

  • one in the MBR which runs in legacy mode
  • one in the the EFI system partition which runs in UEFI mode
    The MBR one only knows about Ubuntu18 because it has not had an update-grubj
    The one in the EFI system partition finds Ubuntu22, but cant find Windows, for some reason we can not determine

So I now have to ask… When you booted in legacy mode, did you go into Ubuntu18?. Because if you did you would have actually got Ubuntu22 , because grub just boots that partition regardless of what it labelled it in its menu.
If you did go into what was labelled as Ubuntu18, I think what happened next was either

  • grub realised the label was wrong and updated it , or
  • you did an update-grub and that changed the label

If all that guesswork is right, you have converted Ubuntu22 to legacy boot, and that solves your problem… Just leave the bios set to legacy boot.

On the comparison with your wifes computer:
hd1,msdos5 - 5th partition on 2nd disk
hd0,msdos6 - 6th partition on 1st disk
So that is just where grub looks for the root filesystem
Not surprising 2 computers differ.

Now another question. Is your wifes machine legacy boot?
It would seem Windows does not like UEFI boot

Regards
Neville

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22

Good morning Neville, I am so grateful for your efforts to help me out!! At this moment everything is fine, my computer runs in Legacy mode and I have got Ubuntu 22.04 LTS and Windows 10 back and working! Answer to your questions: When I first started after changing UEFI & Legacy to Legacy only, I got Ubuntu and Windows in the menu. The Ubuntu version was without doubt 18.04 LTS, 22.04 had disappeared. Yesterday I told you that I thought the system had “healed” itself, because Ubuntu 22.04 was back in the menu and working!! With GParted and Disks I discovered that Linux had installed an extra partition on my second Internal HDD I use for backups only. In boot/grub/grub.cfg I find: Ubuntu 18.04 LTS set root=‘hd0,msdos5’ and Ubuntu 22.04 set root=‘hd1,msdod5’.
I’ll leave my Bios in Legacy only mode from now on.
I ckecked the Bios of my wife’s computer: UEFI & Legacy mode. Hope I’ve not bothered you too much. Thanks very much again!
Regards, Ed

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23

So you have 2 grubs… becausi it boots in either uefi or legacy mode
And you have 2 linuxes, on different disks.
Maybe the 2 grubs are on different disks? It is very confusing.

By all means leave it alone if it works
When you do your next major upgrade you might consider wiping disks and reinstalling everything, just to get a clean start.

Thank you for the great feedback. It helps other people if you complete the story.

Regards
Neville

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