dual boot Kubuntu 20.04 Windows 10

[Qqmike]

nicrnicr, I have read (twice) your post #14, and I understand most of it (kind of). For now, let's follow arsivci, and see what he gets out of this. Or jlittle.

My (casual) observations:

It does look like your Kununtu got installed, sda6. BUT ... it looks to me like it got installed in UEFI mode with sda5 as your ESP.

Whereas, Windows has been using a MBR-type boot. You can see some Boot Configuration Data in sda1, /bootmgr /Boot/BCD; and a boot sector sda2 (but with Legacy System32)?

From UEFI, efibootmgr reports your PC is booting from ubuntu FIRST (and so UEFI).

Unknown MBRs/Boot Sectors -- those are hexdumps of the 512 B sectors which usually contain boot files; listed here as unknown bootloader ... etc. I wouldn't be too concerned for now with that noise in those sectors.

I am not comfortable with Windows.
It sort of looks like your system is booting from a hybrid boot system -- I could be wrong -- part MBR, and part UEFI/ESP. Rod Smith is an expert on this, but he generally advises to stay away from such setups.
I am not comfortable with hybrid booting systems.

Generally, it looks like something made your setup WAY too complex! Only 2 OSs, but look at this output. I suspect Lenovo had a lot to do with this complexity.

Boot-Repair is wanting to simplify things for you by converting to ONLY legacy MBR booting.

As I say, I'd feel more comfortable hearing from others, like arsivci and jlittle.

[nicrnicr]

Thank you jlittle.
I wrote
"I made a 512 MB EFI Partition and a big Ext4 partition (both logical)."
because I didn't install precisely any primary partition. I've been thinking that when one installs a set of partition, they are automatically logical.

Thank you arsivci and Qqmike (especially for reading twice the report).
I bought the laptop second hand and I understood that the seller installed Windows himself.

I wrote "sudo gdisk -l /dev/sda" in the terminal of a live USB:
The answer is
"MBR: MBR only
BSD: not present
APM: not present
GPT: present

Found valid MBR and GPT. Which one do you want to use?"

I suppose that Windows is on MBR and Kubuntu or the begining of Kubuntu is on GPT.

I now have the idea to install Kubuntu as it has been installed on my other Laptop:
Windows_in_3_parts - Ext4 - swap - 4th_part_of_Windows

[nicrnicr]

I think that at the begining you tried to help me to install Kubuntu on a GPT with UEFI.
My Windows is on MBR and Legacy was selected.
Since I turned Legacy in UEFI in the BIOS, I cannot run Windows but I can install an EFI-System partition.
There isn't any EFI-System partition on my other Laptop, and when I put "ls /sys/firmware/efi" in the terminal, the answer is that this doesn't exist, which means that the other laptop is running with legacy.
I might try to turn UEFI in Legacy back in the BIOS.
I will try to install in legacy and MBR. This is oldfashion but I don't care.
Have I been thinking wrong?

But arsivci wrote "If memory serves me right, 20.10+ will not install on DOS/MBR" which means that I won't be able to upgrade.

[nicrnicr]

I deleted the EFI-partition and chose legacy in the BIOS.
I started the computer which proposed me after a long time
- ubuntu
- ubuntu
- ATA HDD0: WDC WD5000LPLX
- PCI LAN: IBA CL Slot 00FE v019
I chose ATA HDD0 and the screen came back to those 4 choices.

[nicrnicr]

I can no longer turn off the computer by pressing the power button. . I have to disconnect the power supply and the battery.

[nicrnicr]

"Please set your BIOS in Legacy mode in order to start your Ubuntu 20.04.2 LTS, then type command [sudo update-grub] in order to add the Windows entry to your GRUB menu. [/U][/FONT]"

Thank you arsivci

I can only start Kubuntu 20.04 from USB and didn't install any Kubuntu. I just tried to install a few times Kubuntu.

[arsivci]

You're running a very fragile set-up as Qqmike observed. Any time sudo upgrade-grub is run by the system, a break is possible since your PC is a train of hacks to run win10 on MBR, possibly upgraded from win8. I really recommend to correct it since you do not seem to have a booting system anyway (though choosing ubuntu from those 4 choices could succeed). Unless it is more than 12-13 years old, your computer should be UEFI capable. If you have a win10 CD lying around or could get your hands on it, it is better to remedy this fragile state, otherwise a bios or win or ubuntu upgrade is likely to break it in the future as this is not a common scenario and will not be tested much, if ever.

1- Verify if it is UEFI capable and switch to UEFI.
1a- You might want to switch off secure-boot while you are at bios. Kubuntu will work just fine with it but if you want to try a new distro in the future, that one may not support secure-boot.
2- Wipe out everything.
3- Make a clean install of win10, UEFI mode.
4- Verify that Windows is booting.
5- Plug Kubuntu usb and restart the system.
6- Do an automatic (guided) install, accept defaults, only adjust the space that will be allocated to Kubuntu using the slider (it is slightly more time consuming than a manual install because the installer will have to shrink the win part).
7- You do not need a separate swap partition, don't worry about it.

It may look scary at first but it's really not. Dual-booting is sensitive and sticking to a well-tested scenario (UEFI-win10-linux) will be much better.

Good luck!

[jlittle]

arsivci has given a great plan... I'll just add a thought.

3- Make a clean install of win10, UEFI mode.

If you can boot the existing windows, extracting its product key might be a good idea; it might save mucking around with MS support.

Even if you were going to run Windows only, if a reinstall is feasible (from an installed software point of view) I would recommend it. I inherited a laptop at work, and I regret not immediately wiping and reinstalling Windows. Eventually I was forced to. (Now the laptop has the Windows install in a VM under Kubuntu, even better.)

[Qqmike]

I agree that arsivci has given a great plan. Frankly, I should have said the same up in post #16. That's what I would do. I am prone to wiping everything and starting from scratch. In some cases, even using dd to wipe the entire drive. But at least re-partition. In at least a few extreme cases I've seen, there can be artifacts lying around, especially at the every end of a disk (which dd will positively wipe). It sounds daunting; but as arsivci encourages, it is really not so bad -- certainly not as difficult as patching up and maintaining a fragile/uncertain setup.

[nicrnicr]

Dear arsivci, dear jlittle, dear Qqmike,

Thank you so much for your help. Even if I didn't do what you suggested me at the end. I could solve my problem thanks to your numerous messages.

I prepared me to buy a Windows 11 (which corresponds to buy the ID or reference number of a Windows 10).
Then I've been thinking that I could try a boot-repair before installing this new Windows.
This made me think that I can look for something (that I forget now). By the way I found someone in the net who had approx. my problem with Ubuntu 18.04. The people who helped him advised him
1) to continue to install Ubuntu with legacy.
Which would erase the GPT part of the memory.
I only deleted the UEFI until recently and there was still a Kubuntu partition which wasn't totally installed.
2) or to change the BIOS of the Windows into UEFI/GPT

Then I've been thinking that Kubuntu 20.04 might refuse Legacy. I looked in the net and find a tutorial: "How to dual boot Ubuntu 20.04 on Windows 10 Legacy MBR"
https://www.google.com/search?client...Pxc8PrO2JwAc21

I don't understand the last part of he's video that I didn't use (He downloads a GRUB software for Windows and adds Ubuntu).

The problem is solved, thank you again :-)