HELP NEWBIE Pls - "Windows failed to start" error on dual boot system

[gold_finger]

Alright -- looked into this and am basically using info from this tutorial and adjusting a few things to adapt it to your situation in steps listed below.

Before you start:

1. Make a live dvd/usb of Ubuntu as noted before.  (If making a usb, use Rufus program for best results.)
   
2. Turn off "Fast Startup" in Windows 8 as noted before.
   
3. To be on the safe side, make a Windows 8 recovery USB if you have a spare usb stick for that.  (Even if you can't do it right now, I'd recommend you do that at some point to make repairing/re-installing Windows easier if you ever need to do that.)
   
4. If you haven't already done so, boot computer and go into UEFI Settings and change boot mode to UEFI.
   

To convert your LL installation to UEFI mode, do the following steps.  (NOTE:  you'll need to be connected to the internet during some of these steps.)

Boot computer with live Ubuntu dvd/usb and hit the <F12> key immediately after power-up to invoke the Boot Menu.  You should see listings to boot your dvd/usb.  Choose the one that corresponds to booting it in UEFI mode.  (NOTE:  this boot menu applies only to the current boot session and is not affected by the change in boot mode you made to the main UEFI Settings Menu above.  That is why you need to specify "UEFI" here separately.)


If you see any warniings about "booting in insecure mode" or not being able to find "/boot/efi ..." just ignore those and continue.


At the grub-screen choose the option "Try Ubuntu without installing".

When the Ubuntu screen appears, click search icon (top left icon) and type X into the search box – the Xterm icon will then appear – click on it to open the terminal.

In the terminal you need to be in super-user mode so type the following:

Code:

sudo su

You need to mount both your installed LL Root partition and the EFI System Partition (ESP) to the live environment.  Do that with these three commands, one at a time.

Mount the Root partition:

Code:

mount /dev/sda11 /mnt

Make a directory to mount the ESP to:

Code:

mkdir -p /mnt/boot/efi

Mount the ESP:

Code:

mount /dev/sda2 /mnt/boot/efi

Now you're going to mount some other directories before you switch to operating directly within the installed LL vs. from the live Ubuntu terminal:

Code:

for i in /dev/ /dev/pts /proc/ /sys/ ; do mount -B $i /mnt/$i ; done

Enter this command to change from operating as root in live Ubuntu to operating as root directly within the installed LL system:

Code:

chroot /mnt

Now enter the following command to synchronize the package database:

Code:

apt-get update

Remove/Purge any grub related packages that might be currently installed on the LL system:

Code:

apt-get purge -y --force-yes grub* shim-signed linux-signed*

A window will then pop-up, entitled Configuring grub-pc, asking if you want to remove GRUB 2 from /boot/grub.... Click on the option <Yes>

Install the correct EFI related grub files to LL that are necessary to boot in UEFI mode:

Code:

apt-get install -y --force-yes grub-efi-amd64-signed shim-signed linux-signed-generic

Then add boot menu entry for EFI firmware configuration; however this may not add a Windows entry.

Code:

grub-mkconfig -o /boot/grub/grub.cfg

Tell grub to install to the ESP (where it will co-exist with the Windows boot loader -- not replace it.)

Code:

grub-install /dev/sda2

Update grub to add boot menu entry for Windows:

Code:

update-grub

Exit the chroot to LL:

Code:

exit

Unmount everything in this order (press enter after entering each line one at a time):

Code:

for i in /sys /proc /dev/pts /dev; do sudo umount /mnt$i; done
sudo umount /mnt/boot/efi
sudo umount /mnt

Your done!

Close the terminal and shutdown computer.

Reboot and you should see grub boot menu offering both LL (shown as "Ubuntu") and Windows.  Test booting into each to make sure everything is ok.

If computer still boots directly into Windows, don't panic.  Just boot the Ubuntu dvd/usb again in UEFI mode, then run this command in a terminal:

Code:

sudo efibootmgr -v

Copy/Paste the output back here for us to see and we'll tell you how to fix booting LL from that output.