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

2 Answers 2


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 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.

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