Can I install Windows after installing Ubuntu on UEFI?

Question

Can I do this? I've heard that you're supposed to install Ubuntu after Windows, as Windows will destroy the bootloader and try to shove itself in as THE OS.

In BIOS, you could only have one bootloader in the MBR, and Windows would obviously overwrite it with its bootloader, and then I would have to get my Ubuntu DVD or USB and use the boot-repair tool from a ppa or do the repair manually.

In the UEFI though, I've heard it can support multiple bootloaders, all stored in a proper partition called the EFI partition, formatted with a proper filesystem, FAT32. Could Windows just add its bootloader into the EFI partition and be done, no overwriting? Or will it still force itself and destroy or not recognize the partition? Will I need to do a boot-repair (or chroot) or not?

EDIT: This is not a duplicate of "How can I install Windows after I've installed Ubuntu?" because that question and topic mostly handled MBR/BIOS booting. While I added my answer on there, the original question, and how it was mostly answered, mostly covered MBR/BIOS booting, which is quite different from UEFI/GPT booting. This allows a specific question and answer dedicated to the topic of UEFI booting, which in this context is so rarely covered. Doesn't help that I feel many newer Ubuntu users install in UEFI only if forced by Windows in a dual boot, and many will avoid it in a single-boot situation to deal with the more familiar concept of BIOS/MBR booting.

Solution

To install Windows alongside Ubuntu, you just do the following:

1. Insert Windows 10 USB
2. Create a partition/volume on the drive to install Windows 10 on alongside Ubuntu (it'll create more than one partition, that's normal; also make sure you have space for Windows 10 on your drive, you might need to shrink Ubuntu)
3. Install the Windows 10.

That's it!

Note: when making sure things are ready for your dual boot, check if Ubuntu is installed in the GPT partition table! While 99% of the time you will be using GPT if you're planning to do this, it is possible to install Ubuntu's UEFI on MBR but Windows 10 does not support that strange use-case. In that situation, convert to GPT if possible. If not, backup and reinstall, and I'd recommend that as it'll be easier.

Comments

[RoundDuckMan]

This question covers UEFI booting explicitly though. The other question was primarily focused on BIOS booting. There's more of my explanation in the original question itself as an edit. I will say I did post my answer on that "duplicate" as well, but having a more modern question with its retrospective answer might be less confusing. Besides, the answer to a question like this is far different from the usual answer to the "duplicate," due to BIOS and UEFI being so different. It's like comparing Pi booting with the BIOS.

[RoundDuckMan]

Ok, so I just delete this post then, or what do I do to set things up right and satisfy this duplicate thing? I posted the answer to this on the duplicate as well, so is it just delete this question and answer and I'm all set? Or is it alright that this answer and question stay as well, with the fact that it has a link to another question with my same answer as one of the answers?

[Fabby]

Don't delete the post. Leave it as is as it's a placeholder that eventually will become more important if people search for "UEFI ubuntu windows"...

[RoundDuckMan]

@Fabby, yeah that was one reason I thought of this, documentation for anything outside of emulating the BIOS way of installation (whether it's using CSM or setting up a UEFI-only installation in the conventional "Windows, then Ubuntu" like BIOS, with the hope in Grub set up like in the BIOS; the only exception is Rod Smith's rEIFInd and other more complex stuff that's only for advanced users) is extremely sparse.

[oldfred]

How you boot install media, UEFI or BIOS is then how it installs for both Ubuntu & Windows. You want to be sure to boot in UEFI mode. Best to let Windows add the partitions it wants as it wants several. Windows may change boot order, it seems to depend on UEFI and how each brand implements it. Windows also turns on fast start up and may turn on UEFI Secure boot, which you do not want if dual booting. Best to have Ubuntu live installer handy, just in case you need to update boot order or even reinstall grub.

[RoundDuckMan]

Actually it didn't turn on Secure Boot (I had to turn it off in order to install Windows 10; it's ironic as KDE Neon worked with Secure Boot right on the live USB) nor any of the other stuff, but I can't be sure about fast boot as there is no setting in the UEFI about that (which BTW, fast boot is about the POST, nothing else, you're maybe also meaning "fast startup," that hibernation garbage that I admittedly forgot to turn off, but will soon enough, if I haven't already, doesn't matter too much as I usually reboot which does a full shutdown and itsn't affected by fast startup).

[RoundDuckMan]

To add further, it didn't change boot order, at least as of now (and admittedly, it would've most likely done it in the installation, if it didn't it's likely it'll never happen), Grub still starts instead of Windows. More like it's the strange behavior of UEFI where it seems to by default to boot first on the bootloader installed first, not the one installed last like the BIOS.

[RoundDuckMan]

And one last thing, yeah I know UEFI installation applies to both OSes. In reality, that should be downright obvious, as systems are supposed to only support one boot method per drive; two would confuse the ever living daylights out of anything that's supposed to kick off the bootloader, whether that's a Pi, an old PC, or one with UEFI.

[karel]

Please copy/paste this answer as an answer to this question: How can I install Windows after I've installed Ubuntu? so that I can upvote it there.

[RoundDuckMan]

Alright. Getting it on there. I also adding an explicit Creative Commons license just-in-case one needs to reuse the answer, because I feel there needs to be more documentation out there in edge cases on how to deal with UEFI.

[RoundDuckMan]

@karel, an extra thing to say: I removed the licensing stuff because I realized all that stuff is under a Creative Commons license anyways, oops.

[karel]

Not only is it under a license, but at Stack Overflow there is a bot that crawls the site looking for deleted code and notifying reviewers to review the deleted code edit to rollback to the previous edit before the code was deleted.

[RoundDuckMan]

That's pretty interesting, going around and finding ways to bring lost code back.

[RoundDuckMan]

Obviously though, it relates to that whole atomic editing system Stack Exchange likes and has for their stuff.

[karel]

There are a lot of reviewer tools that Stack Overflow has that Ask Ubuntu doesn't have. So far Ask Ubuntu has imported two reviewer tools from Stack Overflow. It's a big job because most of these tools are hard-coded for Stack Overflow.

[ubfan1]

One little gotcha: Ubuntu in UEFI mode does not care what disk partitioning is used, gpt or dos. Windows for UEFI mode requires gpt, so be sure your Ubuntu install is on a gpt disk.

[RoundDuckMan]

Yeah, but I'd feel it's obvious one would be using GPT, also Ubuntu's installer uses GPT by default.

[RoundDuckMan]

That said, I'll add a side-note soon to point out that one might need to check their partition table before installing Windows, but I won't dwell too much on it as only power users and early adopters would be the type to make MBR UEFI systems.

[oldfred]

We have seen a fair number of users with Windows in BIOS/MBR and system is newer and then try or do install Ubuntu in UEFI boot mode. Often where system had no operating system/DOS or where they added a drive.

[RoundDuckMan]

@ubufan1, the side note is finally added now. also, lied about not dwelling too much on it, I did in the end, oops. :P

[Fabby]

An edit and an upvote! ;-) (KISS: Keep It Simply Stupid; no one is interested in GatewaysM: just the solution) >:-)