GRUB boot/rescue error

[Quickhatch]

I had to install Ubuntu (16.04.1) on an external HDD for an assignment (had to demo ns-3)

It was successful, but every time I try to boot my Win10 without the external attached, it gives me a grub error saying 'no such device'

I had to restart my PC and boot with my external and use the Windows loader

 

[Quickhatch]

MERGED QUESTION
Question from Quickhatch : "GRUB boot/rescue error"

I had to install Ubuntu (16.04.1) on an external HDD for an assignment (had to demo ns-3)

It was successful, but every time I try to boot my Win10 without the external attached, it gives me a grub error saying 'no such device'

I had to restart my PC and boot with my external and use the Windows loader

 

[TheTechZone]

Now that you dual booted on two different drives windows boots with GRUB but since GRUB is on your external drive it has nothing to boot from. It is like removing your BIOS, software used to boot has been removed, in this case GRUB, and it leaves a hole in the boot. You should try booting with the external drive in then remove it once booted.

 

[TheTechZone]

I think this may work, try installing windows again without the external HDD attached and then you will have windows loader and GRUB.