Ubuntu – why am i unable to dual boot windows 10 with ubuntu 18.04


I have been struggling to dual boot Windows 10 with Ubuntu 18.04. I have Windows 10 already installed with all the latest updates as of 21st July 2018. The problem that I am facing is that when I boot Ubuntu from the USB drive, I am asked to install Ubuntu. When I choose that option, while proceeding I see that there is no option to install Ubuntu alongside Windows.

Only option to erase the disk and other options are available. I looked up in the Internet and found similar problem for Dell XPS model but in that question dual booting was being done with Ubuntu 16.04. In that post it was advised to enable ahci in sata controller option in BIOS mode and to disable fast boot mode. I have done all those things but still option to install Ubuntu alongside Windows is not showing.

ubuntu windows dual boot option

What I am trying to say that above option is not showing but all the rest options from second onwards is showing. The laptop that I am using is Lenovo g5080. I have Windows 10 (64bit) already installed and I don't want my data to be erased. Why am I unable to dual boot Windows 10 with Ubuntu 18.04?

disk management system

disk types and partition

I am also adding screenshots from Ubuntu installation pages. I don't see "install Ubuntu along with Windows" option as shown below :

enter image description here

and partitions in Ubuntu. the free space is what I intend to use for Ubuntu installation

enter image description here

Best Answer

I had a similar issue trying to install Ubuntu 18.04 alongside Windows 10: the Ubuntu installation page did miss the "Install Ubuntu alongside Windows 10" option.

In my case, the cause of the missing option was:

  • my Windows 10 is set up in BIOS / CSM mode (WIN+R -> msinfo32 -> open System Information -> right pane: BIOS Mode shows Legacy), presumably because I had upgraded from Win7
  • in my Mainboard BIOS / Firmware setup, UEFI is not disabled (only "UEFI" or "UEFI+Legacy" options are available, I have set this to "UEFI+Legacy")
  • to install Ubuntu, I had booted an out-of-the-box Ubuntu 18.04 USB stick which (by default) has both GPT/UEFI + MBR/BIOS/LEGACY capabilities, but...
  • here comes the issue: ... since the Mainboard boot device priority was set to boot UEFI USB drives before booting into BIOS USB drives ...
  • ...as a consequence, the Ubuntu USB stick would always boot into GPT / UEFI mode (you can tell by checking e.g. if the /sys/firmware/efi directory exists, see the various hints on the net)
  • and thus the Ubuntu installation does not find a Windows 10 boot record (apparently looks only for UEFI... what do the experts say?)

I did fix the issue simply by:

  • changing the Mainboard boot device priority to boot NON-UEFI devices first (or: you can enter the manual boot menu -> and pick the NON-UEFI USB stick to boot from)
  • and then boot the Ubuntu USB stick successfully into BIOS / MBR mode (no /sys/firmware/efi directory)
  • et voila: the "Install Ubuntu alongside Windows 10" option appears, and installing Ubuntu parallel to Win10 automatically yielded the desired boot menu with Ubuntu and Windows10 to choose.

Converting Windows 10 to UEFI mode was therefore not neccessary for me.

Maybe this helps also in your case...

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