I installed Ubuntu alongside Windows 10 (UEFI). After the successful installation (using the 'install alongside Windows' option, I restarted my machine, but it booted right away into Windows.

What I tried:

  • Change order of boot to Ubuntu. Then it did prompt the Grub screen! But when I select Windows, it shows a "Windows failed to start error, similar to this screen" Is there a solution to this problem?

  • Disabled secured boot.

  • Tried running the following command:

bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi

  • Try to boot into Linux and then install rEFInd (www.rodsbooks.com/refind/installing.html) - I switched to rEFInd at some point when I experienced this. – fstanis Sep 24 '17 at 18:06
  • Thanks for the help. Unfortunately, that does not appear to work – Moody Sep 24 '17 at 18:41
  • Did you install Ubuntu in UEFI boot mode or in BIOS boot mode? They are not compatible and once you start to boot cannot change. Or grub cannot boot other installs in different boot mode, but you should be able to dual boot from UEFI boot menu, often f10 or f12, check your manual. – oldfred Sep 24 '17 at 22:34

This issue is related to your computer EFI that only look for the failback location of the boot firmware. If you can't override the boot menu on computer start up, you may copy the firmware file to EFI/Boot/bootx64.efi of your EFI boot partition. Here the process:

  • Boot with your Ubuntu live CD without installing it.
  • Open a terminal.
  • Switch into permanent root with sudo -s
  • Identify your EFI partition with fdisk -l. Location the partition /dev/sdxx where you see EFI system as type.
  • Mount the EFI partition with mount /dev/sdxx /mnt
  • Rename the Windows firmware (in case of you want revert the change) with mv /mnt/EFI/Boot/bootx64.efi /mnt/EFI/Boot/bootx64.efi-win (you may adapt the path with correct upper case).
  • Copy the Ubuntu firmware with cp /mnt/EFI/ubuntu/grubx64.efi /mnt/EFI/Boot/bootx64.efi
  • Umount properly the partition with umount /mnt
  • Reboot your system

There is a software called boot-repair that always fixes my boot problems with grub. You can read about it at https://help.ubuntu.com/community/Boot-Repair

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