Updated to Windows 10 killed my Debian GRUB (U)EFI Boot

Submitted by Nikolaus Polak on Sat, 08/01/2015 - 14:18
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After the Windows 8 -> Windows 10 Upgrade the Debian testing UEFI Grub2 only showed it's rescue shell. On Debian, I use full disc encryption and have a seperate boot partition - here is how I fixed my Grub without using some LiveCD or Live USB:

On the Grub rescue shell, enter the following - in case you don't know which partition holds what, you can also try > ls (hd0,gpt7)/ [Enter] to get some content information. I knew that number 7 was my dedicated boot partition and number 8 the encrypted root file system.

grub rescue> ls
# shows all partitions
grub rescue> set prefix=(hd0,gpt7)/grub
grub rescue> set root=(hd0,gpt8)
grub rescue> insmod normal
grub rescue> normal

Then I got the normal boot menu, including background picture again and could boot Debian linux completely.
Enter shell to make the changes permament:

# update-grub
# grub-install 

Partly source, which helped me finding the right way: https://www.linux.com/learn/tutorials/776643-how-to-rescue-a-non-booting-grub-2-on-linux/

(including the comment regarding dedicated boot partition)

Submitted by Jean-Bob (not verified) on Sun, 11/01/2015 - 02:04

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After an upgrade from 7 to windows 10 while I had a Linux Mint 17.1  installation on another partition I had the same kind of problems. Suddenly my Grub bootmanager was missing and it wasn't possible anymore to get to the partition where my Linux Mint files were installed. I searched on the internet and found out that I wasn't the only one who had encountered these kind of problems. The partition of Linux suddenly had become unallocated space and couldn't be read anymore.
There were offered many solutions but most of them were not very clear to me. One of the advices was to try a program as Testdisk which had been a solution for many so I tried that first.
With Testdisk I discovered that at least the files of my Linux installation still were there. It even offered the possibility to copy those files to paste them on an external hard drive but when I tried that I couldn't find that hard drive with the program installed on Windows, and when I tried it with a live CD I could find my external hard drive but when I pasted the files nothing happened.
So I looked further for another solution. I tried Hirens Boot Disk, I tried Easus recovery  but they didn't gave me the solution for my problem. They couldn't recover my lost files or restore the linux installation,
Then I read about another recovery tool called Free Minitool Partition Wizard and I decided to give this a chance.
I installed it on Windows 10 and ran the program. It offered me the possibility to recover the Linux partition by first marking the unallocated space where my Linux Mint installation should be and then after first a quick scan run the Partition Discovery Wizard on the left side of the window. First I had to mark ALL the unmarked boxes of the partitions it had found - also the ones with the Windows Installation on it -  and at the end I only had to push on apply. Much faster than I had expected it was finished and the unalllocated space was again a partition with EXT4 on it.
That gave me hope again. After that I used the Live Linux Boot Repair CD to reinstall the Grub which I needed to get the choice again to boot into Linux Mint whenever why wanted. To be sure I checked - after I had booted up my PC with that Boot Repair CD - if I could read the files ( and back up them at once )  and I could. I made the default repair offered by that CD and when I booted up again the Grub bootloader AND my Linux Mint installation were there again.
I hope people who encounter the same kind of problems as I did will find any help in this post of my experiences  because the most solutions for this problem offered on the web untill now weren't enough to get me out of this problem because I an prpbably not geeky enough to understand.

Thanks for your comment - as this never happened to me, where did you notice that your Linux partitions have become "unallocated space"?
From a Linux LiveCD/USB with gparted?