Ubuntu – Windows 10 does not boot from GRUB

bootbootloaderdual-bootgrub2windows 10

I have a problem. I have installed Windows 10 on /dev/sda1 and Ubuntu 14.04 on /dev/sda6. I use GRUB as bootloader but (I don't remember since when) when I choose Windows in the menu it does not boot and returns to GRUB.

I tried to reinstall GRUB but nothing worked so far.
If I run sudo update-grub the system considers a Windows 7 bootloader and writes the menuentry. But why does it not boot?

UPDATE#1:

I followed your instructions cl-netbox and reinstalled GRUB as follows:

sudo mount /dev/sda7 /mnt
sudo mount -o bind /dev /mnt/dev
sudo mount -o bind /sys /mnt/sys
sudo mount -t proc /proc /mnt/proc
sudo cp /proc/mounts /mnt/etc/mtab
sudo chroot /mnt /bin/bash
grub-install /dev/sda
update grub

Now it does not return into GRUB after selecting Windows in bootmenu but Windows still does not boot. There is only a black screen showing _

Could that have something to do with the following message after executing?

bootrec.exe/scanos

Searching for Windows-installations was successful. Number of identified installations: 1
[1] C:\Windows.old\Windows
(sorry for bad translation)

I have updated from Windows 7 to Windows 10

Best Answer

  • Maybe the Windows BCD store is corrupted.

    To fix this boot from Windows install media.

    On the "Install now" screen choose -> Repair your computer
    In the System Recovery Options select -> Command Prompt

    Execute the following commands:

    bootrec.exe /fixmbr  
    bootrec.exe /fixboot  
    bootrec.exe /scanos  
    bootrec.exe /rebuildbcd  
    

    Shutdown the computer and boot from Ubuntu install media.
    Reinstall GRUB and run the update-grub command afterwards.
    Now you should be able to boot into Windows from GRUB menu.

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