Dual Boot Goes Straight Into Windows

Hey everyone, I had Manajro install as my only OS (I'm new to Manjaro/Arch, but a long time user of Debian based distros). There were a few things I needed to run in Windows so I decided to dual boot with Windows. I resized my Manjaro partition using Gparted (after unlocking the encryption), then I installed Windows on that new partition.

Well now my machine boots directly into Windows with a Grub menu of any sort. I have tried a number of things in the forums but nothing seems to work. I have tried booting into UEFI (Manajro Live flash drive) and Legacy modes. I have tried the bcdedit commands and the grub config commands, the bcdedit commands claimed successful but it still booted directly into Windows 10. The Grub related commands either don't work or some of them work but it just boots into the live usb flash drive. I tried detecting EFI bootloaders too, it finds nothing. I'm not quite sure where to go from here other than backing up the data from the partition (I can access it via the live flash drive) and starting from scratch. I need to dual boot because I don't have a product key for Windows 10, it only works if I reinstall on this machine because it detects the hardware and knows I started with a valid copy of Windows 7 then upgraded.

Any help is appreciated. I'm a DevOps Engineer so feel free to be detailed and technical.

Please boot up your Manjaro live usb, connect to internet, open a terminal, run the following commands and post the output back here.

sudo parted -l
(that is lowercase L)

efibootmgr -v

Use the </> button to format the pasted text.

I told it to ignore the issue it found instead of fix, I didn't want it hosing the Windows partition too. It still boots directly into Windows.



Since this is about a Legacy installation, Windows has written its bootloader to the MBR of the disk thereby overwriting Manjaro's bootloader.

You could restore Manjaro's bootloader (Grub). Boot up your live usb,connect to internet and follow carefully the instructions in the following link for Bios system.

Note when asked for which system to chroot after the command sudo manjaro-chroot -a put 1 (instead of 0).

Good luck!

I don't see a link in your post. As for "legacy" what do you mean?

I am sorry, forgot the link. Here it is:


Here is some explanation:

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I tried a number of things to get this to work. I followed a few rabbit trails, but nothing worked.

So when I try manjaro-chroot -a or with sudo all I get is a massage after several seconds, no menu selection like I've see other people get.

==> ERROR: You cant mount 0!

My primary Manjaro partition is encrypted and I opened the encryption, it still gave me the same error after trying again.


Yeah, I remembered that, but it never asks which system. The command just runs, then it goes back to the prompt with that error I stated above, I never see the a menu/question of which one I want to choose.

Try the manual method and see if works better.

I got really far into it, but ultimately I can't get dosfstools installed. The last command produces the

EFI variables are not supported on this system.

Then I followed the fix to that but I keep getting db and URL errors for when I use pacman to install the dosfstools. I was able to install grub and the other thing, so it's not an network issue. I tried deleting tha db and trying pacman-mirror commands as well as -Syyu and it just produces the same errors. At this point I spent MUCH more time on this than it would have taken for me to back up my files from the drive and reinstall. Do you suggest an official guide for dual booting Manjaro with Windows 10 already installed? I want to do it right.

Your installation is a Legacy/MBR not an UEFI. Therfore:


You know, I was following the instructions and was wondering if you had said to start at a specific point but couldn't find it, apparently I need more coffee. :smiley:

:coffee: :coffee:


Yeah, all I get with the first BIOS related command, after chrooting, is:

grub-install: error: cannot find EFI directory.

To clarify I only have sda1 (primary Manajro volume) and sda3 which is the swap I believe. sda2 is Windows 10 and sda4 is a recent volume I created trying to get the UEFI stuff working.

I don't understand why you keep at trying to install the bootloader for a Legacy system using command that is intended for UEFI. There is no EFI direcrory in a Legacy/MBR/Bios installation.

Pleas go back to the instructions, chroot using the manual method and run:

grub-install --recheck /dev/sda

If this won't work, I don't know what will.

Well, the first instruction under the BIO section is:

grub-install /dev/sda (which I put sda1 infro sda)

I got that error I just mentioned. I skipped step 1 under BIOS and went on to step 2 like you just said and got the same exactly error:

grub-install: error: cannot find EFI directory.

I wasn't trying to use an UEFI command that time.

Then I don't have any idea what is going on. I am sorry. Perhaps some other forum member will chime in.

OK, well thanks for giving it a try and sticking with me.

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