Ubuntu 18.04, Ubuntu 20.04 and Window boot loader issue

vanguard478

3/25/24, 11:40 AM

I am having issue with the GRUB bootloader, where the Focal OS isnt showing at all - just Ubuntu 18.04 and Windows are shown as boot options. I had installed Windows (/dev/nvme1n1p3) -> Ubuntu 18.04 Beaver(/dev/nvme1n1p5 )-> Ubuntu 20.04 Focal (/dev/nvme0n1) on my PC with two drives (/dev/nvme1n1 and /dev/nvme0) . After installation everything was working fine. I was able to see the GRUB boot loader with all the OS. The bootloader was configured on /dev/nvme1n1 . Partitions of /dev/nvme1n1 .

grub.cfg for Beaver : Ubuntu 18.04
grub.cfg for Focal : Ubuntu 20.04

Not sure but I think the problem occurred after I mounted the Focal drive while inside the Beaver and tried writing some files. Although I wasn't able to write anything on the mounted drive point because of write privileges. This is the screenshot of the mounted disk of Focal when I am inside Beaver. I was doing this since the Beaver partition is smaller and I needed to used the larger Focal disk from inside Beaver.Mounted Disk of Focal inside Beaver

I tried using the boot-repair utility using the recommended option but it is not working out. Only Beaver and Windows options are being shown. Can some one please help me fix the grub boot loader. I can access all the files on the Focal Drive without any issue.

1 + 5

boot

grub2

dual-boot

bootloader

oldfred

3/25/24, 1:37 PM

Is 20.04 installed in UEFI boot mode or old BIOS? How you boot install media, is then how it installs or repairs. Post link from Summary report for suggestions as it recommends when asking for help. Please copy & paste the pastebin link to the BootInfo summary report ( do not post report), do not run the auto fix till reviewed. Use often updated ppa version over somewhat older ISO with your USB installer or any working install. https://help.ubuntu.com/community/Boot-Repair

vanguard478

3/25/24, 1:51 PM

Hi, * 20.04 was installed using UEFI boot mode. * Sorry but I already performed the boot-repair using the "Recommended" option by using the Live USB of 20.04 . When I am in 18.04 (installed OS) the os-probe doesnt recognize the 20.04 installation `/dev/nvme1n1p1@/EFI/Microsoft/Boot/bootmgfw.efi:Windows Boot Manager:Windows:efi` . However when I use the live usb of 20.04 it recognizes the 18.04 installation. So I performed the recommend repair. Even then the menu items were not present. This is the repair summary [link](https://paste.ubuntu.com/p/YGJkdMW3j9/)

vanguard478

3/25/24, 1:59 PM

After the repair from Live USB of 20.04 didnt work I copied the `menuentry` from the `grub.cfg` of 20.04 and pasted it in installed Ubuntu 18.04 `/etc/grub.d/40_custom` . After `sudo update-grub` I am able to see the boot menu items for Ubuntu 20.04. Here is the link for the modified `40_custom` [link](https://pastebin.ubuntu.com/p/dHCGHwPtzb/)

vanguard478

3/25/24, 2:00 PM

I tried updating the grub by going into the Advanced boot option of Ubuntu 20.04 but it is just resetting the `40_custom` file and not adding the entries for 20.04.

oldfred

3/25/24, 6:22 PM

IF you have this error, then os-prober cannot see drive. "sfdisk: /dev/nvme0n1: does not contain a recognized partition table" It looks like you formatted drive without partition table. Almost all tools need to see a partition table, not a formatted drive. You in effect have a very large floppy type drive, that may be mounted with that type of driver. But you really need to start over & add partition(s), and use gpt, not old MBR(msdos).

Score:0

Ubuntu

thewade

3/25/24, 12:23 PM

You may need to enable os-prober. Edit the config file /etc/default/grub and add GRUB_DISABLE_OS_PROBER=false is the option does not appear in the file. Save then run sudo update-grub.

+ 1

vanguard478

3/25/24, 12:33 PM

I check the `/etc/default/grub` . It already has an entry `GRUB_DISABLE_OS_PROBER=false` When I run the `sudo os-prober` , I get the following output `/dev/nvme1n1p1@/EFI/Microsoft/Boot/bootmgfw.efi:Windows Boot Manager:Windows:efi `

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