How do I delete Ubuntu 18.04

Check in Ubuntu22
Do a df
You should see something mounted to /boot/efi
If not , you need to find the EFI partition and mount it first.

I assume your machine is a uefi boot?
If it is a legacy boot, it is all different.

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I am putting the finishing touch to a legacy boot of Ubuntu 22.04 that is running Ubuntu 22.04 and Windows XP.

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afbeelding

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That seems OK.
Now do
update-grub
It should find Ubuntu22 and Windows (and Ubuntu18 if you
have not removed it yet)
If it does not find Windows… add the line
GRUB_DISABLE_OS_PROBER=“false”
to the file
/etc/default/grub
and try again.

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Neville, I have not removed Ubuntu18 yet, I wanted to do that after the Grub procedure would have worked. I sent part of the monitor output to show that /boot/efi exists. However the last line gave an error (in Dutch) saying "no installation device mentioned¨.
What is meant here?


My Ubuntu default grub. All of the grub entries can be edited and saved, this is just one way I boot Ubuntu, if it was Gentoo, then it would be a little different.

Thanks for your input, Daniel! I have the same /etc/default/grub contents.

You know you can still install and use Grub Customizer to edit and remove grub entries and update grub so, so that Ubuntu 18, can be safely removed. I have it installed on Ubuntu and Debian, and it has not given me any problems. I had to use it to rename my Windows install.

This may not be a simple solutikn for you

But

Back up any important files
Reinstall windows from new on a formatted disk
Then install ubuntu new along side

That way the grub will be written correctly by the system rather than trying to work iut which us which …

Thats the way i would go for easy life

Is your BIOS set to legacy boot?
What I gave you for grub install is for EFI boot
For legacy boot it is
grub-install /dev/sdb
to put it on disk sdb
and you do not need an EFI partition

Sorry, I could not read the Dutch

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Thanks very much for all your efforts!! Ubuntu 22.04 runs fine without problems. Since I did not use 18.04 any more, I decided to delete it to make more space on HDD1. I now spent many hours to achieve this and I see so many advices like “reinstall Windows” I seldom use etc., that I don’t understand it any more. So I will just keep on working in Ubuntu 22.04 and leave the rest as it is. Although I tried hard I always had difficulties understanding Grub. (I might have Gruberitis, ha, ha) Thanks again Neville, with kindest regards, HHarry18

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Hi @HHarry18 ,
Yes grub can be tricky.
The official grub manual is here

Regards
Neville

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Thanks again Neville. I’m going to study the manual this time, only had some notes about Grub… Had no problems with my other computers and laptops as far as Grub was concerned, only with my much used desktop. My wife has the same desktop with pre installed Windows and Ububntu 22.04 installed by me. No problems whatsoever. Regards, HHarry18

Three important things that grub interacts with

  • the boot method… legacy or efi
  • the type of partition table … msdos or gpt
  • which Linux controls grub … probably Ubuntu18

If you can tell me what your machine has for each of those,
we can work out how to safely redo grub so that you can remove Ubuntu18 and still be able to boot.
No need to rush this… we want to get it right.
Regards
Neville

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Sorry for having bothered you so far, Neville. As you may still know I already had problems with Grub before, because I did not understand how it really worked. It started when I installed Ubuntu20, before this no problem. I wanted 22.04 to be the first entry and whatever I did, no success! Thanks to the Manual I came to the conclusion there must be TWO Grubs on my desktop. How silly of me not to have noticed that before!! It now becomes obvious to me that when I changed something in Grub, I did so in the 22.04 version. Now that I changed the order in Grub 18.04, the computer boots up with 22.04. For the time being I’ll keep it that way. Thanks again for everything Neville (and others). With kindest regards, HHarry18

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Yes it can be. I understand where @HHarry18 is coming from. Everything is working fine, so leave it be. When you don’t fully understand something and fear that you can make matters worse and maybe not being able to boot the PC.

If I was in Harry’s shoes, how would I take a backup?
A) Backup the entire disk of each OS? That would take a lot of time and a lot of backup HDD’s.
B) Backup just the OS of each system?
C) Backup just the EFI or MBR area of each disk?
or D
D) Perform B & C on a backup HDD for each system?

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Most important thing to backup is @HHarry18 's personal data. He can always replace the OS.
So I vote for A) even though it is slowest way.

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That is OK… one grub on each disk.
I do that deliberately… then if one disk fails, I can boot from the other.
It can be a bit confusing keeping track of which Linux controls which grub.
Try selecting which disk to boot from at the BIOS boot menu. That will test if you can boot from either disk.

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Thanks everybody for all your help!! I am a bit wiser now with your advices! It made me study possibilities to make Grub listen to me on this computer. Thanks again! HHarry18

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I am going to add this to this post!!! I recently installed Ubuntu 22.04, but due to my Nvidia GT430 graphics card and kernel version 6, Ubuntu 22.04 was completely useless, so I have regressed backwards to Ubuntu 20.04, and it is able to run the Nvidia GT430. So here I am on Ubuntu 20.04, for the foreseeable future, or until, the brains at linux allows the nvidia-390-drivers to work in kernel version 6.