Kali / Windows : GRUB Problem

[lechienblak]

Hello,

I have a DELL laptop running with Windows.
I wanted to install Kali Linux 2020 on an external hard-drive.
To make the installation, I did it through the laptop, with a USB bootable key with Kali LINUX installer and the hard drive.
The Installation went well, and now, when I plug my hard drive on this laptop and I start my laptop, it directly goes on the OS Kali LINUX.

The problem I encounter is when I don't plug this external harddrive, it doesn't start on my Windows OS and I don't know how to do.
I have the following Error :
Welcome to GRUB!

error: no such device : ab21ed22-614c-****-****-**********75
error: unknown filesystem
grub rescue>

-------------------------------------------------
I don't know how to do. I want to be able to start on my Kali Linux when the external drive is plugged (even manualy if necessary) but I also want my Windows OS to launch automatically when I start my computer.

I suspect, during the Kali Linux installation, the graphical interface asked me where I want to install BOOT Loader and if I remember well, I chose /dev/sda2/ but I am not sure.

I am looking for help!
Thank you

 

[Vrai]

Is this machine using Legacy BIOS or UEFI BIOS?
If UEFI BIOS you may be able to access the Windows boot loader from the UEFI Boot Menu.
Likely the Grub Boot Loader overwrote the Windows boot sector.
If that is the case you would need to 'rebuild' the Windows boot sector.
You could try running "update-grub" when booted into Kali but then you would always need the external drive with Kali plugged in when booting.
Whenever I install Linux in a dual boot configuration with two hard drives I will disconnect the one drive while installing on the other for that reason.
Linux will boot Windows just fine but Windows will not boot Linux.
You will need a Windows installation or rescue disc to access a Windows command prompt in order to rebuild the Windows boot loader.

Unplug the Kali drive - insert the Windows installation/rescue disc - restart the machine - repair the Windows boot loader - reboot to verify it is working - shut down - plug in Kali drive - boot up - use BIOS Boot Menu to choose which to boot. Boot into Kali and run "update-grub". You may find that you can now boot Windows directly or choose it from the Grub boot menu.

 

[lechienblak]

Hello @Vrai Merci for the answer!

If I use a bootable key with windows installer to reinstall it, do you think it will erase on the content on my pc ? (The content I want to save in on Windows) Actually it is safe and still there on the internal drive.

Thank you

 

[lechienblak]

By the way, it uses Legacy BOOT

 

[Vrai]

Hello @Vrai Merci for the answer!

If I use a bootable key with windows installer to reinstall it, do you think it will erase on the content on my pc ? (The content I want to save in on Windows) Actually it is safe and still there on the internal drive.

Thank you

If you use the Windows installation media as a "Live" disk in order to access a command prompt it will not effect your data.
If you re-install Windows it may go 'sideways' and not save your data even though Windows has an option to preserve your personal files.
Do a search for "repair Windows boot loader" and you will find numerous tutorials and guides on how to do it. I have performed this operation a number of times and it is quite easy
I would try the boot loader repair trick first. You will not lose any data doing that.

 

[lechienblak]

Thank you @Vrai, I'll try this way