I tried to install Ubuntu alongside windows 8.1. I disabled secure boot and made sure UEFI was enabled and moved the DVD above Windows Boot manager in the boot order. But the Ubuntu installation still doesn't detect windows on the system. It gives me the options to erase all data on the hard drive or do something else, and if I do something else then I get a list of partitions.

What else can I do to get the installation to detect windows?

Thanks in advance for any help.


Below is a link to a resource that walks you through the dual-boot install process for Ubuntu and Windows 8.1. It outlines the steps of the installation as follows:

  1. Back up Windows
  2. Create a bootable Ubuntu USB disk
  3. Shrink the established Windows partition
  4. Turn off(disable) fast boot
  5. Turn off(disable) secure boot
  6. Install Ubuntu from boot-disk
  7. Boot repair
  8. Fix the bootloader
  9. Reboot into Ubuntu
  10. Reboot into Windows

The steps I have listed are a concise version of the posted link. There are detailed instructions between listed steps, be careful to read and follow each; failure to do so could result in data loss, corruption, or system failure.

  • If done properly and on a bug-free EFI, there should be no need for steps #7 or #8. Those steps are normally only needed if you incorrectly install in BIOS mode. Step #4, as described on the page to which you linked, is often unnecessary, although it is sometimes required; but disabling Fast Startup in Windows is necessary. (Although the page uses Windows to do the task, it's actually disabling a firmware feature.) Step #5 should be unnecessary, too, although on rare occasions it is required.
    – Rod Smith
    Jun 1 '14 at 19:34
  • Fair enough. If I understand the premise of the provided link properly, the idea is to illustrate a "tried and true" method of installation, so unnecessary steps may have been included for consistency or assurance. Not entirely sure, I'm not enormously familiar with the process. When I installed Ubuntu on my laptop, I replaced Windows 8, because I had no use for it. Limited experience with dual-booting anything newer than Vista. Jun 1 '14 at 19:39
  • 1
    I believe that what's happened is that people who don't know what they're doing have stumbled upon an inefficient and sub-optimal method that barely works. They've then promoted that method without figuring out a better way to do it, and it's spread from there. To learn how to do it more efficiently, read my page on the topic or the Ubuntu community wiki on the topic. Both provide tips for doing it more efficiently.
    – Rod Smith
    Jun 4 '14 at 1:48
  • @ RodSmith, Point taken. Jun 5 '14 at 4:52

I ran into a similar issue when attempting to dual boot Ubuntu 18.04 on a machine running Windows 10 with legacy BIOS. During the Ubuntu install process, the installer did not recognize the Windows 10 OS.

I ran diskmgmt.exe in Windows and saw that the disk had an MBR partition:

MBR Partition

Previously, I had Windows 7 installed and got upgraded to Windows 10. I think this is how I ended up getting Windows 10 with an MBR partition. From my understanding, Windows 10 needs to have a GPT partition in order to have UEFI BIOS, otherwise you'll end up with legacy BIOS.

This seems to cause the error during the install process. Ubuntu 18.04 has a UEFI BIOS; Windows 10 will also need to have a UEFI BIOS, or it won't be recognized.

I ran the mbr2gpt tool that comes installed with Windows 10 Creator's Edition:


This procedure will allow you to change the Windows partition from MBR to GPT. You'll need to get a WindowsPE USB to run this tool:


After changing the partition, you'll be able to switch to UEFI mode in your BIOS. Once the BIOS was set to UEFI, the Ubuntu installer recognized the Windows 10 OS and I was able to dual boot both systems.


Click Do Something Else. You will see your partitions on the drive. From there assign mount points, create new partitions, whatever you want to do. Just dont format the EFI partition and your Windows partition

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