I have a Macbook Pro 13 in. 2020 on Big sur 11.5 and am trying to get bootcamp again. I previously had it up until a few days ago when I tried to increase my bootcamp storage by creating a new partition. It was 60 gb partition formatted as MS-DOS (FAT). Easy, simple right? when restarted my computer, the bootcamp hard drive was no longer accessible on the startup disk. After restarting my computer and deleting the new partition, bootcamp no longer showed up at all. At this point, I removed bootcamp entirely.

I redownloaded the Windows ISO and used the bca to go through the process. Seemed the work just fine until i recevied this error message: "Windows cannot locate the disk and partition specified in the unattended answer file's setting. Make sure the setting references a valid partition and restart the installation"

After a going through multiple different reasons I narrowed the issue down. When bca creates the BC and OSXRESERVED partition to set up windows 10, bca would put the ISO and everything it needs to run bc on the OSXRESERVED partition. I reset the PRAM and SMC mutliple times and reran BCA as well. It's been a constant cycle over the past 3 days and I would appreciate any help.

Below is my diskutil list with the bootcamp and extra partition after my last attempt.

meganreynolds@Megans-MacBook-Pro ~ % diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                        EFI ⁨⁩                        314.6 MB   disk0s1
   2:                 Apple_APFS ⁨Container disk1⁩         255.0 GB   disk0s2
   3:       Microsoft Basic Data ⁨OSXRESERVED⁩             10.0 GB    disk0s3
   4:       Microsoft Basic Data ⁨BOOTCAMP⁩                229.4 GB   disk0s4
   5:                        EFI ⁨⁩                        83.9 MB    disk0s5
                    (free space)                         5.5 GB     -

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +255.0 GB   disk1
                                 Physical Store disk0s2
   1:                APFS Volume ⁨Macintosh HD⁩            15.3 GB    disk1s1
   2:              APFS Snapshot ⁨com.apple.os.update-...⁩ 15.3 GB    disk1s1s1
   3:                APFS Volume ⁨Macintosh HD - Data⁩     149.6 GB   disk1s2
   4:                APFS Volume ⁨Preboot⁩                 285.9 MB   disk1s3
   5:                APFS Volume ⁨Recovery⁩                626.1 MB   disk1s4
   6:                APFS Volume ⁨VM⁩                      2.1 GB     disk1s5

meganreynolds@Megans-MacBook-Pro ~ %

  • Also im sorry I'm very very limited on technology knowledge, this has all been a learning process. I apologize if my wording or description of my issue is confusing. Jul 25, 2021 at 10:19
  • Can you post the diskinfo as text rather than an image. Images are unsearchable & unreadable for people with limited vision, reliant on reader software. Paste, then select & hit Ctrl/K [not Cmd, Ctrl] to format it.
    – Tetsujin
    Jul 25, 2021 at 10:38
  • 1
    @Tetsujin I believe I did it correctly Jul 25, 2021 at 16:59
  • You probably are not suppose to have the second EFI partition (disk0s5). The AutoUnattend.xml file is the unattended answer file. In your case, I believe this file is generated by the bca. It may be possible to install Windows without this file. Jul 26, 2021 at 3:42
  • @DavidAnderson how would I do that Jul 26, 2021 at 6:02

4 Answers 4


I had the same frustrating problem on an iMac18,3 running Big Sur.

After a lot of thinking and searching on the internet I came up with a following workaround for this and a couple of other issues and error messages:

  1. Prepare a bootable USB drive for Windows 10 (with Windows 10 Installation Media here: https://www.microsoft.com/en-us/software-download/windows10). Normally, this has to be done on a Windows computer - I used a VMWare Fusion virtual machine. To create the drive using a Mac, please search the internet for a solution as I didn't need to do it.

  2. Remove the USB drive.

  3. Start Boot Camp Assistant, choose the size of the volume for Windows, run the assistant. IMPORTANT! Carefully wait for the moment when the Mac restarts and immediately press and hold Option.

  4. When the option to choose the startup drive appears, normally there should only be one drive on offer - the Windows installation drive created by Boot Camp Assistant. DO NOT choose this but instead insert the USB drive and, when it appears as "EFI boot", select it and press enter (make sure your Mac allows booting from USB, if not - restart in Recovery mode and check in Startup Security Utility).

  5. The Windows installation starts from the USB drive. At the point where you need to choose the partition to install Windows to, choose BOOTCAMP.

  6. Let the Windows install.

  7. After the installation, go to the BootCamp folder on drive D: (OSXRESERVED) and run Setup. This will install the missing drivers. I think this part is basically what Boot Camp Assistant would do under normal circumstances.

The rest seems to be standard Boot Camp functionality.


I would assume that if you previously used the Boot Camp Assistant to install Windows, then somehow when you removed Windows the partitioning was not restored correctly. This probably resulted in the second attempt to install Windows to fail. Below are the commands to remove the existing Windows installation. Afterwards, you should attempt using the Boot Camp Assistant to reinstall Windows. If you fail again, then instructions could be posted on how to install from that point.

diskutil erasevolume free none disk0s5
diskutil erasevolume free none disk0s4
diskutil erasevolume free none disk0s3
diskutil apfs resizecontainer disk0s2 0



I had this same issue, but I was eventually able to get it loaded, I am not a tech by any means. I did a lot of digging around. if you're desperate to get it installed give it a shot. So, this answer will require some work. Here is how I was able to get Windows 10 Pro on my 2019 MacBook Pro 16 Core i9 32GB RAM.

After a lot of digging, I found that the Bootcamp app has had many updates. The latest version on my MacBook Pro (Sonoma) was giving me the error you mentioned my steps that worked were:

  1. Back up data

  2. Downgraded to macOS Ventura. Why? Apparently, it works better when calling for the Mac partition. Again, I'm not a tech and I don't know the ins and outs as to why.

  3. Install Windows using Bootcamp normally within macOS Ventura

Upgrade to Sonoma (latest OS when writing this) or whatever OS you want. Reload data

My journey was long and it included the following hurdles:

  • macOS not formatting my USB to MS-DOS FAT32 when loading Ventura to USB with Sonoma prior to downgrading. (Found a fix)

  • Internet Recovery not working. (Found a Fix)

  • Blue Screen after installing Windows driver-related (Found a Fix)

  • Touch Bar dark not working in Windows (Found a fix)

  • Windows Support drivers not installing ( Found a Fix)

After all this, I am not running Windows 10 Pro on my MacBook Pro with no issues even have AutoCAD and Sketch-up Pro Working :)

Hopefully, this helps someone. If not, I recommend getting a tech, not an Apple tech as they will not help you install Windows.


If you have trouble with drivers including a dark, non-working Touch Bar in Windows, follow the steps at Download and install Windows support software on your Mac.

This may or may not work for you but I'd give it a shot. Basically, try installing Windows in older versions of macOS then load the update back. That's all I got.


I had 2 internal SSDs and 1 internal HD that I had installed and nothing worked until I tried removing them all from the equation. Once I unplugged all of them, my Windows was able to install using Bootcamp like normal with the ISO downloaded from Microsoft.

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