I had many problems to fix the grub on my Ubuntu Gnome 14.10.

In my case, I formatted both Linux and windows, but this can help if you only format your Ubuntu.

  1. Go to the BIOS interface, disable security boot and change legacy boot mode to UEFI boot mode.

  2. Install your Windows 8.? (normal procedure)

    PS: if you do not want change you previous Windows you can start here.

  3. Go to the BIOS, stay disable BOOT and change UEFI to Legacy.

  4. Start your media (pen drive or whatever) and install Ubuntu Gnome.

  5. That steps are important. You should create 4 new partitions where, this link can help as well: http://pplware.sapo.pt/linux/dual-boot-com-windows-8-e-ubuntu-12-10-uefi/

    way   system     type        size of
    /boot ext2       primary     (300Mb?)
    /     ext4       logical     (as you want)
    /home ext4       logical     (as you want)
    /swap                        (4000Mb)

    You can install your Ubuntu now, BUT make sure that you are installing in /boot, /dev/sdaX. (X should be de directions of your boot system)

  6. Now you have Ubuntu Gnome installed, so lets fix the grub. Again, go to the BIOS and set Legacy mode to UEFI, still disable boot...

  7. Start Ubuntu from your media and choose the option, try Ubuntu. In this steps you gonna reconfigure your grub. An easy way is https://help.ubuntu.com/community/Boot-Repair. You can follow these steps and install. My advise is, after installed choose the option advanced settings and check if the path of your boot from Ubuntu and Windows are ok, then apply. The program can do some questions and say to you past some commands at the terminal, just do that and when it ask for remove your grub choose NO!

    PS: I had many many problems here. In my case when I installed Ubuntu Gnome using the boot mode in UEFI it never fixed the grub. When I installed this in legacy mode not works as well! It only works when I installed the Ubuntu in legacy mode, then I reboot it go to BIOS and change the Legacy to UEFI and after in Ubuntu try mode from media and install boot repair.

  8. When boot-repair finish the procedure you can reboot your computer.

    In some cases this is enough to grub2 ask which OS you want, if no, probably there will be a black screen when you turn on the computer. If it happens, go to the BIOS, again rsrs, change the security boot mode to > Enable and still boot fro

  9. I hope everything goes well for you! =D

2 Answers 2


This "question" doesn't pose a question; it's a tutorial of its own. I don't know what it adds to the frequently-referenced Installing Ubuntu on a Pre-Installed Windows 8 (64-bit) System (UEFI Supported). Furthermore, I STRONGLY disagree with a key part of this procedure: Step #3 changes the boot mode from EFI/UEFI to BIOS/CSM/legacy. This is a mistake, which is corrected later in the procedure, in steps #6-8. It's almost always better to install Ubuntu directly in EFI mode. Doing so will obviate the need to fix GRUB, since it will be set up correctly in the first place.

Some people seem to have trouble getting the Ubuntu installer to boot in EFI mode. I suspect that most of these problems are caused by creating an Ubuntu boot medium in weird ways. In this context, "weird" means anything but using dd to copy the raw image to a USB flash drive, or cdrecord or similar tools to burn a CD-R. This page doesn't recommend anything specific for that, so it's unclear what the author used. Tools like Pen Drive Linux and Unetbootin work by copying files to the target medium. Most such tools were written before EFI became common, and older versions don't create the right EFI boot files. Even some newer versions require activating special options that aren't set by default to create an EFI-bootable image. The bottom line is that these tools might or might not create an EFI-bootable drive, depending on what tool you use, what version of said tool you're using, and what options you select.

That said, even copying an image with dd is not 100% guaranteed to work. It usually does work, but these images are Frankenstein monsters; they're created to work on both USB flash drives and CD-Rs, and to be bootable under both BIOS and EFI. This is done by laying things down in an unusual way, which usually works or sometimes causes problems. Thus, if you can't get a dd-created image to boot, you might have to resort to some other tool; but if you do, you should carefully examine options to find the ones that will create an EFI-bootable image.

For more on this topic, see my Web page on installing Linux under EFI. It's really not that hard, although there are potential pitfalls that can trap the unwary.


You could also enter this in the grub, and this is after you installed Ubuntu, and on a pre installed Windows 8, and it is enter in this producer after menu entry enter this:

set default to this: 2/default=

and this after menu entry of windows 8.

  if   fi   fi-uuidf   set root=ext4

and after echo this:

 uuidf /boot/efi/EFI/ubuntu/MokManager.efi

and it might work also.

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