Cannot start something different than Windows 10 after update

Question

I had dual boot. Windows 10 and Ubuntu 16.04 LTS. Yesterday after updating Windows grub stopped to work and I was unable to do anything with the PC. It is desktop PC. When I tried to boot with live USB and I choose: "Try Ubuntu" or "Install Ubuntu" I got the following error:

[  0.020613] ACPI Error: [\_SB_.PCI0.XHX_.RHUB.HS11] Namespace lookup failure,
 AE_NOT_FOUND (20160930/dswload-210)
[  0.20619] ACPI Exception: AE_NOT_FOUND, During name lookup/catalog (2016093
0/psobject-227)
[  0.020644] ACPI Exception: AE_NOT_FOUND, (SSDT:xh_rvp10) while loading table
(20160930/tbxfload-228) 

and PC froze and the black startup screen gets filled with blurred text. I tried to fix grub but there was no partition that which can be recognized as some Linux partition. After that I tried to use Windows live USB and to clean MBR. Windows managad to update and I have Windows now but when I try to boot from Ubuntu Live USB I got the same error. How to fix Ubuntu installation? I tried with Ubuntu DVD also and I got the same error.

Answer 1

When you install Windows, Windows assumes it is the only operating system (OS) on the machine, or at least it does not account for Linux. So it replaces GRUB with its own boot loader. What you have to do is replace the Windows boot loader with GRUB. I've seen various instructions for replacing GRUB by mucking around with GRUB commands or some such, but to me the easiest way is to simply chroot into your install and run update-grub. chroot is great because it allows you to work on your actual install, instead of trying to redirect things here and there. It is really clean.

Here's how:

1. Boot from the live CD or live USB, in "Try Ubuntu" mode.
2. Determine the partition number of your main partition. GParted (which should already be installed, by default, on the live session) can help you here. I'm going to assume in this answer that it's /dev/sda2, but make sure you use the correct partition number for your system!

3. Mount your partition:

   sudo mount /dev/sda2 /mnt   #Replace sda2 with your partition number
   

4. Bind mount some other necessary stuff:

   for i in /sys /proc /run /dev; do sudo mount --bind "$i" "/mnt$i"; done
   

5. If Ubuntu is installed in EFI mode (see this answer if you're unsure), use GParted to find your EFI partition. It will have a label of EFI. Mount this partition, replacing sdXY with the actual partition number for your system:

   sudo mount /dev/sdXY /mnt/boot/efi
   

6. chroot into your Ubuntu install:

   sudo chroot /mnt
   

7. At this point, you're in your install, not the live session, and running as root. Update grub:

   update-grub
   

   If you get errors or if going up to step 7 didn't fix your problem, go to step 8. (Otherwise, it is optional.)

8. Depending on your situation, you might have to reinstall grub:

   grub-install /dev/sda
   update-grub # In order to find and add windows to grub menu.
   

9. If everything worked without errors, then you're all set:

   exit
   sudo reboot
   

10. At this point, you should be able to boot normally. If you cannot boot normally, and didn't do step 8 because there were no error messages, try again with step 8.

Sometimes giving GRUB2 the correct configuration for your partitions is not enough, and you must actually install it (or reinstall it) to the Master Boot Record, which step 8 does. Experience helping users in chat has shown that step 8 is sometimes necessary even when no error messages are shown.