FIX: Can’t Boot Windows 10 After Installing Ubuntu

Ivan Jenic
by Ivan Jenic
Troubleshooting Expert
Passionate about all elements related to Windows and combined with his innate curiosity, Ivan has delved deep into understanding this operating system, with a specialization in drivers and driver troubleshooting. When he's not tackling... Read more
Affiliate Disclosure
  • Probably you received the No boot disk has been detected or the disk has failed message when you reinstalled your Ubuntu system on your Windows device. Don't panic because your disk is not broken. Read our complete solution below.
  • If you have corrupted Windows files read our guide with the best tools to repair corrupted files on Windows 10.
  • If you want to read more about Ubuntu, please read more about it in our dedicated section.
  • If you experienced any other Windows 10 errors look no more. Check out our Windows 10 errors hub.
Can't Boot Windows 10 After Installing Ubuntu fix
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Most likely when you reinstalled your Ubuntu system on your Windows 10 device, you might have gotten some error messages when trying to boot into Windows 10 operating system.

Although this issue is not very common, I will explain to all our readers how you can fix it and prevent it from happening in the future.

The error message that you might get is this: No boot disk has been detected or the disk has failed.

But you don’t need to be alarmed because in the majority of the cases your disk is not broken.

The first step you should take is to check if you can boot into Ubuntu. If you can, then it is a Windows 8 or a Windows 10 issue and you can fix it by following the steps listed below.

What can I do if Windows 10 won’t boot after Ubuntu install?

1. Use diskpart

  1. Place a USB or a DVD in the Windows 8 or Windows 10 device with Windows recovery media.
  2. Reboot the Windows device and you should get to the Advanced options window.
  3. In the window that shows after the device boots from the USB or DVD, you will need to left click on Troubleshoot.
  4. After left-clicking on Troubleshoot, you will need to select Advanced Options feature.
  5. Left-click on Command Prompt feature.
  6. The Windows 8 or Windows 10 device will restart and then you need to choose your account to sign in.
  7. Now after Windows restarts, you will get to a black window which is the command prompt.
  8. In the command prompt window type diskpart.
  9. Hit Enter on the keyboard.
  10. Type in the following command sel disk 0.
  11. Hit Enter on the keyboard.
  12. In the command prompt type list vol
  13. Hit Enter on the keyboard.
  14. The EFI partition you have there should be a FAT32 partition.
    Note: Depending on what volume your EFI partition is you will have to follow the next steps accordingly
  15. We will take for example that the EFI partition is Volume 2.
  16. Now type in the command prompt window sel vol 2
  17. Hit Enter on the keyboard.
  18. Type in the command prompt window assign letter=a
  19. After you hit Enter you will get a message saying DisKPart successfully assigned the driver letter or mount point.
  20. Type in the command prompt exit.
  21. Hit Enter on the keyboard.
  22. Now you will still have the command prompt window in front of you but you will be take out of the DISKPART> feature.
  23. Type in the command prompt window cd /d a:EFIMicrosoftBoot
  24. Hit Enter on the keyboard.
  25. Type in the command prompt window bootrec /fixboot
  26. Hit Enter on the keyboard.
    Note: The bootrec /fixboot command will repair your selected drive.
  27. Now type in the command prompt window the following command ren BCD BCD.old
  28. Hit Enter on the keyboard.
  29. Type in the command prompt window bcdboot c:Windows /l en-us /s a: /f ALL
  30. Hit Enter on the keyboard.
  31. Remove the USB or DVD with the recovery media and try a reboot of the Windows 10 system.

2. Additional solutions

If the steps listed above did not solve your problem, here are some additional solutions that you can use:

  • Download and install Boot Repair. With the help of this tool, you can repair boot errors on dual-boot machines. You can use it when you can’t boot Ubuntu after installing Windows 10, or when you can’t start Windows 10 after installing Ubuntu.
  • Boot in UEFI Mode. If you don’t use this boot mode, you may experience various boot issues when launching your Windows 10 OS. Keep in mind that OEMs usually install Windows 10 in UEFI mode by default. If you install Ubuntu in legacy mode, you won’t be able to boot to Windows 10 simply because you installed the two operating systems under two different modes. Make sure that both operating systems are installed in UEFI mode so that you can boot booth of them.

After the restart everything should be back to normal and you should be able to boot into Windows with your Ubuntu still running. If you have any questions on fixing your Windows 8 or Windows 10 after installing Ubuntu, use the comments below to let us know.

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Frequently Asked Questions

  • You need to boot into the BIOS and choose Ubuntu as the default operating system for booting. If it sounds too complicated, follow our step-by-step guide on how to do that and more.

  • The best way of dual-booting Windows and Ubuntu is to install them in this order. However, if you already installed Ubuntu you can install Windows after. If you have any problems afterward, check our excellent guide to fix any inherent such issues.

  • Set your computer to boot from CD, insert the Ubuntu CD and boot into a live session. You can use a LiveUSB also if you have one. You can now install Boot-Repair and then run it.

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Avatar Mohan Raj

Hi Team,
Please help me with the below error.
Everything went well except the last 29th step.
Error: Failure when attempting to copy boot files
What to do at this point …