I have the .iso image of Ubuntu 15.10 that a friend gave to me. I have a pre-installed Windows 10. When I mount the image and run wubi.exe, it gives the following error:
Wubi does not currently support EFI.
Please tell me how to install (dual-boot) Ubuntu (with Windows). My FastBoot service is off and Windows is installed in UEFI mode.
You can try creating a different partition through windows and then installing with custom installation(when you boot with the USB or CD there is an option after you press ''Install Ubuntu'' instead of install alongside Windows or delete windows). Here is a program that you can try using and a guide along with it: Safely Create Partition for Windows 10 with Free Software
It seems that you can't use wubi with EFI enable.
Try to disable EFI from your bios and do the followings:
Installation with wubi: requires to resize your NTFS windoze partition from Windoze Disk Management to make free space and then you must create a second NTFS partition for Ubuntu, Note that wubi will install Ubuntu on the second NTFS partition and Ubuntu will be slower since NTFS is not a GNU/Linux file system, you will see the instructions just choose what you want, dual boot etc.
Installation without wubi with EFI enable: requires to resize your NTFS partition of windoze to make free space for Ubuntu and set your pc bios to boot from the cd now all you need to do is boot from cd and follow the instructions, is pretty straightforward, will also ask you about dual boot.
Ubuntu on Ext4 partition is much faster since is a file system for GNU/Linux.
Installation without wubi is the best way to go. (recommended)