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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.

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    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. Feb 25, 2019 at 3:54
  • 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? Feb 27, 2019 at 6:07
  • 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"...
    – Fabby
    Mar 1, 2019 at 20:21
  • @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. Mar 3, 2019 at 19:00

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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.

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  • 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.
    – oldfred
    Feb 20, 2019 at 18:07
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    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.
    – karel
    Feb 21, 2019 at 8:58
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    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.
    – karel
    Feb 21, 2019 at 18:37
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    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.
    – karel
    Feb 21, 2019 at 18:43
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    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.
    – ubfan1
    Feb 21, 2019 at 20:06

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