Restore dual boot with Ubuntu when Windows 10 update overrides the UEFI settings

As a Linux user it’s now very rare that I run Windows on my home computer, but when I do it’s usually because of something important. At the moment it’s because I’m taking some exams on my MSc course and the remote proctoring software only supports Windows and Mac.

It’s therefore rather important that my laptop is able to boot into Windows occasionally, but it’s a shame that Microsoft doesn’t seam to have the same concern for stability that I do. If they did then I would think it at least basic courtesy to warn me when a Windows update could leave my computer unusable for several hours and will trample all over the settings I had previously configured.

Fortunately this happened just after my exam, as if this had happened before then this would have been much, much worse than just wasting several hours of my time.

It all started with what I believe is the Windows 10 Anniversary Update. This is a significant update to Windows 10 adding new features in addition to security and bug fixes. As this is a big update then I would have expected a bit of warning – perhaps a “Do you want to proceed with the update now?” or similar. Microsoft has other plans, presumably they don’t want people to skip the update (as users have avoided with the big jump to Windows 10), so they just made it part of the normal “Shutdown and install updates option”.

It took sometime for the computer to shutdown, but the problems became apparent when trying to boot the laptop up again. It first went into the installing updates which was very, very slow. After about an hour I thought it had crashed, but in fact it was still installing the update and a short while afterwards I saw the status creep up to 26% complete. It then continued very slowly until it reached 36% which left the following screen:

The screen says that this will take a while, but this was getting ridiculous, so I gave up on what I was trying to do and went to bed. I woke up the following morning to see that it was still trying to install the update.

Although the screen said “Don’t turn off your PC” by this stage I had little other choice than to force-ably power down the computer. I then rebooted and Windows 10 rolled back the update restoring a working version of Windows.

It sounds like I’m not the only one to have suffered problems with these Windows 10 updates as seen in this story (ThaiVista).

It was tempting to leave disable the windows update and leave the operating system as it is, but leaving a system without recent updates is generally a bad thing, so I then spent several more hours updating all the drivers I could find and re-trying the update. I believe that it now has the latest updates installed and appears to be working, although that was only the start of my problems…

Windows 10 prevents booting into Ubuntu

As I mentioned previously I’m really a Linux user and my laptop primarily uses Kubuntu, which is a variant of Ubuntu Linux. I had already made several configuration changes to my computer to ensure that dual boot worked well, but Microsoft appears to have had other ideas, as since the update it was no longer possible to boot into another operating system. These are the changes I had to make to be able to boot into Grub and hence boot into Linux.

I don’t know whether this is deliberate, that Microsoft doesn’t care what impact the updates have on the user, or that they don’t know what they are doing.

Turn off fast startup

The first thing is to disable fast start-up in Windows 10. This is needed to ensure that the computer full shuts down allowing a different operating system to be booted. This is something I had already done previously, but that has now been reset back to it’s previous setting.

To prevent the fast start-up then the “fast start-up option” needs to be unchecked.
As you can see Microsoft makes this option really easy to find, just to goto:

Start -> Settings -> System -> Power & Sleep -> Additional Power Settings -> Choose what the power buttons do -> Change settings that are currently unavailable -> Turn on fast start-up (recommended)

Make sure that there is no check mark against that option.

Restore EFI to Ubuntu’s Grub loader

The update has also removed Linux from the UEFI loader (replacement for the legacy bios on 64-bit computers). Once again Microsoft has overwritten the changes I have made and makes it difficult to set it back.

First check the file name matches the one I have on my computer which is “\EFI\ubuntu\grubx64.efi”.

You can’t view EFI directly in Windows Explorer etc., so instead right click on the Windows logo and choose:
Command Prompt (Admin)

Choose a drive letter that isn’t in use (I used j: ) and then mount the first partition on the disk drive.
mountvol j: /s

You can then navigate into that drive using:
j:
dir

and cd into the appropriate directories.

Check that there is a file called:
\EFI\ubuntu\grubx64.efi
If not then you may need to perform the restore from a Ubuntu rescue disk.

If that file does exist then it can be set as the default boot option by entering the command
bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi

Check that the dual-boot works

That should be it, it should now be possible to shutdown from Windows and choose Linux (Ubuntu) or Windows from the Grub menu (assuming that is how it was previously set-up).

If that doesn’t work and you need to check the UEFI options directly then from Windows 10 goto Windows logo -> Settings -> Update and security -> Recovery and choose Restart Now which is under the Advanced startup option.

When it boots into the recovery mode choose
Troubleshoot -> Advanced options -> UEFI Firmware Settings and then reboot.

You should then find yourself in the UEFI settings where you can make changes such as disabling Secure Boot.