I'm trying to get dual boot to work on my laptop in seperate hard drives. I've done this in the past successfully in my old laptop with only one hard drive. Since I have two, let's call them SSD1 and SSD2.

I have Windows 10 installed on SSD1. Recently bought SSD2 and installed Debian 8. During installation, windows was detected in SSD1 and added to grub. I changed the boot priority in the BIOS to boot SSD2 first, since grub is located there and it should manage booting to Linux or Windows.

Debian is working fine. However, if I choose windows in the boot screen, the following message appears:

BOOTMGR image is corrupt. The system cannot boot.

Now, here's the funny thing: if I change the BIOS boot priority to SSD1 first, I can boot into windows just fine. MBR's were not even pointing wrong. As a matter of fact, I'm posting this Superuser question in windows right now.

How can I get windows to load from grub? Can someone tell me why this does not work? Separate hard drives maybe?

Anyway, I'd be happy to select OS/Drive on BIOS, but it simply takes too much time as I have to actually dig in the BIOS menu every time I want to change OS.

Any help appreciated!

EDIT1: I'm using MBR on both disks (not GTP) and BIOS (UEFI disabled).

UPDATE1: Following the suggestions in both answers, I first repaired grub with the boot-repair CD. While this did something (it added a second windows entry to grub), it was not necessarily good as neither entry 1 or 2 can get to windows ( BOOTMGR image is corrupt. The system cannot boot). Afterwards windows could not load, so I did repair the MBR with a Windows 10 recovery CD. Automatic repair didn't do it, so I had to input the following commands in the command line:

`bootrec /fixboot`
`bootrec /fixmbr`

After this, everything came back to the original state in this thread: I can boot into Debian or Windows but only if I choose the corresponding hard drive in the BIOS BBS boot priority.

Still not solved. Any other ideas?

  • 1. There is function key on every computer called "boot device selection" usually F12 key. 2. Post more information on disk style - MBR or GPT? Is firmware BIOS or UEFI? – snayob Apr 17 '17 at 12:51
  • Hi @snayob, thanks for your reply! True, but the boot device selection menu only let me choose if I want to boot from the CD drive, USB or a hard drive - it doesn't let me choose which hard drive I want to boot from. That's defined in the BIOS by a hard drive priority sequence. Can be done, but takes about 1 minute, unpractical for dual boot. I think it uses MBR, but I'll confirm that later today and add the info in an edit. I'm using BIOS (UEFI disabled). – Diogo Duarte Apr 18 '17 at 13:24

After you move disks, partitions (eventually add/delete partitions) the principle for fixing boot is always:

  1. Fix Windows boot

  2. Fix GRUB boot

in that order.

Boot configuration should be such that Windows must be able to boot alone without the help of any other boot loader/manager!

What does Windows 10/8/7 use for booting with BIOS firmware (and MBR style disk):

  1. MBR

  2. PBR of active partition

  3. bootmgr on active partition

  4. BCD on active partition

in that order.

A Windows 10 installation/repair USB/DVD can be used to fix boot in this case.

See fix Windows 10/8/7 boot for help on repair steps.

For fixing GRUB you can use a Linux live CD/USB.

Be aware that after a Windows 10 version upgrade/update it possible that Windows will overwrite MBR (overwrite GRUB boot code in MBR)!

Suggestion - use Windows boot manager to dual-boot Windows and Linux.

  • Hey @snayob. As I understand, what you are stating is the typical procedure for repairing boot after dual-boot setups, which I've done in the past. As much as I'd like to repair the windows boot, I can't for the sole reason that it's not broken. (And yes, I've tried. Nothing changed, no big surprise there). Windows can already boot by itself if I select SSD1 by default in the BIOS menu. As for you suggestion: when I install new kernels on Linux, I'd have to go through a painful process of adding new kernels to the boot menu or stick with 1, which might always go wrong, right? – Diogo Duarte Apr 22 '17 at 16:33
  • What do you mean by " painful process of adding new kernels to the boot menu"? update-grub is not painful at all ;) Windows chain loads GRUB, not kernels. – snayob Apr 23 '17 at 21:53
  • oh, really? wow, that sounds good to me, thanks! Anyway, after some search I have the feeling that windows cannot be launched by grub, even though it recognizes it, because grub is installed in SSD2. I think moving grub to SSD1, where windows is, should do it, but not sure. Any thoughts on this? – Diogo Duarte Apr 24 '17 at 10:59

Whenever grub is messed up I use https://sourceforge.net/projects/boot-repair-cd/ . This fixes grub automatically. It did it successfully every single time I used it.

  • If your answer does not give better solution or more information better to write a comment – yass Apr 19 '17 at 20:24
  • Trying it now, thanks. Quick question: does the boot-repair CD do anything other than run "update-grub"? I've done it in Debian already, didn't change a thing. – Diogo Duarte Apr 22 '17 at 16:37

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