I have Linux Mint and Windows 8 installed on my Lenovo laptop side by side (on different partitions of the same HDD) and booting in UEFI mode. I usually boot Windows from GRUB but I can also get it to boot from the BIOS boot menu. I would like to upgrade to Windows 10.

  1. Will it work? Is there any chance I will break something?
  2. What do I need to back up to make sure I can go back if something goes wrong?
  • re: Backup -- make a complete disk image and verify it. Before any major OS change, or even Windows updates, I would do this anyway (I've become more blasé about Linux updates, though, which have never broken my dual-boot systems). – DrMoishe Pippik Apr 17 '16 at 1:26

When you upgrade from Windows 8 to Windows 10, there's a very significant chance that the upgrade will update the Windows boot loader (EFI/Microsoft/Boot/bootmgfw.efi and related files on the EFI System Partition [ESP]) and (more importantly) adjust the boot order to render the Windows boot loader the default. This change will look very much like a boot loader replacement on a BIOS-based installation, but the solution is different. The easiest way to recover in Windows is to install the third-party (but freeware) EasyUEFI program and use it to adjust the boot order so that Mint's boot loader (probably called ubuntu in the list) is the default. Alternatively, you can use the text-mode bcdedit in Windows, bcfg in an EFI shell, efibootmgr from an emergency boot of Linux, or possibly a feature in the EFI's own user interface.

There's always a chance of creating significant new problems when doing a major OS upgrade. I recommend you back up your entire hard disk, or at least all your personal data. If you don't already have a backup and recovery plans, now is the time to set that up. Proceed without such a backup at your own peril. There are dozens of products for doing this sort of thing. Personally, I use ntfsclone in Linux to back up Windows partitions and tar to back up Linux; but other people have other preferences.

  • After Windows updates its boot loader, will GRUB pick it up, or will I need to configure it again? – ondra.cifka Apr 19 '16 at 22:09
  • It should use the same filename it did before, which means the old GRUB entry should continue to work. – Rod Smith Apr 19 '16 at 23:12

I had the same issue and I could update to windows 10 in my HP laptop, but no without problems.

When I updated I had problems with boot (the computer changes the loader to windows boot loader instead of grub) and when I changed to use grub the windows MBR becomes corrupt and I had to solve the problem with a repair image and using the command fixmbr... This solves the problem temporally because each time the bios was updated the default loader changed to windows instead of grub. Nowadays I'm working fine with windows loader instead of grub.


1- Will it work?

Yes, but probably not in the first try.

2- Is there any chance I will break something?

Yes, but with a repair disk and a time probably you could repair it.

3- What do I need to back up to make sure I can go back if something goes wrong?

The most important is to have a repair disk and a copy of all your important data in case you have to reinstall the OS.

Here you have a more detailed guide on how to upgrade.

  • 1
    You are talking about the legacy system but my question was about UEFI. I also went through what you describe with the MBR a few years back. But I never tried to tinker with my new UEFI setup, and that's why I'm asking this question. – ondra.cifka Apr 18 '16 at 20:27
  • If your Linux Mint release has UEFI support there is no problem. – Angel Sanchis Apr 19 '16 at 10:30
  • EFI-mode booting definitely adds its own twists, but this answer is still accurate in its broad overview. – Rod Smith Apr 19 '16 at 13:41

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