[Solved][GRUB Problem] grub rescue but the installation done on external drive

I already configured the order of booting, as you said sometimes I get no OS found errors but there a direct method in my machine to boot from usb/optical drive without going bios.

If you install on external, it should be logical to install grub on the external drive (check first…)

I'm planning to re-install everything,
now windows won't boot if I didn't connect my ext drive for the grub menu.
being able to go to windows (with my ext connected) , and if I delete the partition I created on the ext hard drive I guess I get will grub rescue should I delete mbr file manually if so where to find that ?

Trying to recall...(installed so many different OS's I cannot remember specifically for manjaro :upside_down_face:)

At installation (use manual, advanced or whatsit called)
To install to another drive mbr, there is a device drop down bar
Or maybe when selecting bootloader, type in device (sda, sdb, sdc)
To install to own partition, at bootloader location choose 'system'

After installation, at terminal (same for all OS's - this I won't forget :laughing:)
sudo grub-install /dev/sdc
sudo grub-install --force /dev/sdc5

Reminder -

mbr is not a partition (it is the first sector for the drive). Normally do not need deleting. We can just override it with another grub-install to it. But if you want to 'manually delete' there is a specific 'dd' command for it (always careful with dd - it is called disk destroyer for a reason).

right at this moment,
if I delete the partition (created on the ext disk) when booted on windows, if I reboot windows I guess I'll get the GRUB- rescue menu (will I?), how to fix this (the above method will not work since there's nothing to boot I have deleted the partition on ext disk)

What is the question again?

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so if I'm deleting the partition created on my ext disk, when booted on windows.
If I reboot the windows again (note at this point the only os is windows I have deleted the partition on the ext disk) since there's mbr file on windows I'll will prompted to GRUB-rescue menu ie https://i.imgur.com/owenKtD.png (how to fix this now? or is there a way to avoid this while deleting the partition )

So before you set up on deleting or overriding any mbr...
So you want to override sda mbr with windows boot
make sure manjaro is also on sdb mbr as well

Repeat - have manjaro in sdb mbr as well.
Then go ahead and restore your windows boot on sda
In meantime you can still boot manjaro (and windows) with

And when windows boot is restored in sda,
boot windows by starting computer.
boot manjaro by "bios set-up to boot from external drive"

Then you won't get to grub rescue but to a grub menu.

Am I missing your question somewhere?
Or are you missing my answer?

@AgentS, where is your post on setting bios to boot from sda or from sdb?

@AgentS, where is your post on setting bios to boot from sda or from sdb?

Here it is.

I'm not sure where I'm missing.

If unsure, do both (recommended)
sudo grub-install /dev/sda
sudo grub-install /dev/sdb
sudo update-grub

I did both and this, https://i.imgur.com/agnJBA2.png (found windows on dev/sdb1)

right now I'm promoted to Manjaro screen to choose windows and manjaro.
suppose If I choose windows and boot into that and then delete the manjaro on my ext disk and restart my machine
I will not get the manjaro screen at start in addition I don't boot into windows either. (grub-rescue menu)

(or am I missing something?)

If you have set manjaro grub to both

Try it. After setting to both. Go to bios and boot from external drive. Try it first before getting windows boot on internal drive.
Do this as many times as you like to be sure you have this grub menu before fixing sda windows boot. Can you try it first before you write again the same stuff? (not to be rude, but please)

I know you want to reinstall Manjaro.
Just go ahead.
If you reinstalled manjaro (properly) you won't have a problem booting windows, right.
Of course, if you delete manjaro partition (before installing manjaro) you won't boot anything (including windows). Unless you install windows boot in sda first.

Isn't this obvious?

Seems like you missed my question,

I'm getting a GRUB menu I can boot into windows and manjaro (no problems after updating grub)IMG_20190324_090635
this menu (I don't have pic of previous page it has options of manjaro and windows)

Of course, if you delete manjaro partition (before installing manjaro) you won’t boot anything (including windows). Unless you install windows boot in sda first.

in windows after deleting manjaro partition I should repair the boot so that it should be free of grub.

You should repair the windows boot before deleting manjaro.
Unless you just want to reinstall Manjaro immediately and that is fine.

ok thanks for making my dumb mind clear.

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I have cleaned everything (*successfully) and about to reinstall but this comment made me to think that's my purpose is wrong,

If you fully install Manjaro to the external drive, it can run on one computer and save changes and data. But if you try to use that drive on another computer, it probably won’t work, since the hardware (especially video) is different

from this

well, whatever I'm installing it again no matter what
where to specify Mbr to install on hard disk. https://i.imgur.com/YLnJCc2.png (I don't find any options here)

This comment was made some time ago but now we have 'video-linux' now, non-proprietary graphic driver. Install 'non-free' and you'll be fine. Linux progresses fast, ya?

I think, slightly further down in the installation at "bootloader" installation.
Choose the external drive (if you want windows boot on the internal drive).
Again the reminder to check disk notation using 'lsblk -f'.

And anyway, unless you mess up real big time, there's this link you used (and helped) that you can get back.

I don't think I've said this before (more to the contrary) but 'you're playing it too safe'.
Be 'reckless' for a change. You might learn something if it does not work out.
As they say, "Experience is what you get when you don't get what you want."
And experience is a great teacher. :rofl:

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Be ‘reckless’ for a change. You might learn something if it does not work out.

:sweat_smile: I get it. I don't even know what GRUB was when I installed.
this just increased my interest overall (soon or later I'm going to migrate fully), really thanks for spending time.

Edit: I posted your guide in r/ManjaroLinux yesterday for someone who had prob with grub, it seems he fixed and thanked me (felt unfair) so I'm letting you know you're doing a great job.

Just to raise a thing which should not be missed.
If you don't have any Linux/Manjaro installation on internal drive, you have to "Repair Windows boot" with a Windows method. Most common is with a windows installer disk. Because you won't be able to boot internal Windows without external drive attached.
And I suggest you don't install grub to internal drive, unless it's a rescue action (I mean for a permanent setup).
I hope you won't get lost in the so many suggestions :roll_eyes::wink:


Thanks, I did repair my windows boot (using command prompt and repair tool)

P.s: I have installed grub on ext disk (/) this time and Running Manjaro..:upside_down_face:


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