*Edit. I got it fixed! More information at the bottom.

I did a clean install of Ubuntu on a separate SSD from Windows.

After the installation Windows won't boot. I have tried removing all other drives from my computer and booting up with only the Windows drive. After this I'm greeted with the following message "reboot and select proper boot device".

I'm suspecting that installing Ubuntu has somehow also affected the Windows drive.

Is there any way to fix this, or am I doomed to reinstall Windows?


I had Ubuntu installed in Legacy mode (while W10 in UEFI). Ubuntu had installed the bootloader on the same SSD as Windows 10 for some reason (even though Ubuntu is installed on a separate disk).

I'm glad I did not do a clean install of Ubuntu in UEFI as this would've left the problem remaining on the windows drive.

  • 1
    did you use windows 10?? if yes, before install ubuntu you must disable the window fast boot
    – Deki
    Sep 24, 2017 at 15:20
  • @karel I did check up on that but it was of no use to my problem. I recently tried to use the Windows recovery (USB) and automatic repair with no results. Also tried to manually fix the issue through CMD but still no results. I also ran Boot-repair on Linux but it didn't allow me to tick windows files and I'm quite unsure if it will even try to fix a separate drive from the Linux install folder.
    – Teknosielu
    Sep 25, 2017 at 0:22
  • That is a very old version of bootinfoscript. Better to use newer fork or use Boot-Repair's report which includes the newest fork as first part of its report. Post that link so we have updated info. You have UEFI Windows and may have BIOS Ubuntu but not sure. Script may not be showing Windows .efi boot files as it is too old? But you need Windows .efi boot files in ESP - efi system partition and then in UEFI boot Windows entry. That may need Windows repairs.
    – oldfred
    Sep 25, 2017 at 3:46
  • You can use Boot Repair's Advanced options to uninstall grub-pc and install grub-efi-amd64. That converts the Ubuntu installation from BIOS boot to UEFI boot, the same firmware as most recently manufactured laptops with Windows pre-installed have. Source: askubuntu.com/questions/217904/…
    – karel
    Sep 25, 2017 at 15:24
  • When in BIOS boot mode, grub default installs to sda, unless you use Something Else install option and choose location of boot loader. With UEFI grub always installs to the ESP - efi system partition on drive seen as sda and both Windows & Ubuntu have separate folders with .efi boot files in ESP. UEFI is also a boot manager and users can boot from UEFI if grub is not working to boot another system.
    – oldfred
    Sep 25, 2017 at 16:34

1 Answer 1


Ubuntu had installed the bootloader on the same SSD as Windows 10 for some reason, even though Ubuntu was installed on a separate disk. Installing a clean installation of Ubuntu in Legacy mode while Windows 10 was installed in UEFI mode solved the problem.


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