Dual boot Grub change to Manjaro?

I have a dual boot system, consisting of three drives (below).

Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 2099199 2097152 1G 83 Linux
/dev/sda2 2099200 1000214527 998115328 475.9G 8e Linux LVM

Device Boot Start End Sectors Size Id Type
/dev/sdb1 * 2048 303946009 303943962 144.9G 7 HPFS/NTFS/exFAT
/dev/sdb2 303947776 305014783 1067008 521M 27 Hidden NTFS WinRE
/dev/sdb3 305016832 468856831 163840000 78.1G 7 HPFS/NTFS/exFAT

Device Boot Start End Sectors Size Id Type
/dev/sdc1 2048 1050623 1048576 512M b W95 FAT32
/dev/sdc2 1052670 468860927 467808258 223.1G 5 Extended
/dev/sdc5 * 1052672 468860927 467808256 223.1G 83 Linux

I have Fedora 32 OS on sda, Windows 10 on sdb, and Manjaro KDE Plasma 5.27.8 on sdc.
I recently reinstalled Fedora because I was having issues with it updating.

Now, I have changed the bootloader device to that of Fedora, but want to change it back to that of Manjaro. How may I accomplish this please?

Welcome to the forum! :vulcan_salute:

If you can boot into Manjaro as installed, you can skip the following step. If you cannot, boot up from the Manjaro USB in live mode, open up a terminal, and then issue the following commands. :point_down:

sudo su -
manjaro-chroot -a

Select your Manjaro installation from the menu.

If you can boot up from the installed Manbjaro, then the above is not necessary, of course. Now proceed as follows…

You probably want Manjaro’s GRUB to detect and list your other installed systems, so check the file /etc/default/grub and make sure that the line GRUB_DISABLE_OS_PROBER=false is not commented out, and that it’s not set to true. :point_down:

nano /etc/default/grub

If it needs changing, do that and save the file. Now reinstall the boot loader, as follows… :point_down:

grub-install --recheck

If you booted up from the live USB, exit the chroot with exit and reboot the system. Manjaro’s GRUB should now be the one in control, and should list the other operating systems in its menu. :wink:

Incidentally, you probably should call it a triple boot system now, or more commonly referred to as multiboot (for more than two). :slight_smile:

Edit:- Initial suggestion presumed each OS was installed as UEFI.
Suggestion removed.

This disks looks like msdos parted with MBR, right? Are you booting this OS in BIOS mode?

Are the other disks gpt parted and booted in UEFI mode?

You cannot mix boot modes if you want to boot all OS from grub’s boot menu, technically not possible.