Bootcamp to generate Windows 10 USB key - Needs NTFS partition

Question

I am trying to use Bootcamp to generate a Windows 10 USB key (64GB). I use Diskutil to initialize the key as MS-DOS FAT with MBR. The Bootcamp Assistant selecting the three options on the dialog box. It all works fine, but when I use the key to boot and finish the installation it tells me it cannot install Windows on that partition and that it needs an NTFS partition instead.

Thing is, the partition was reformatted by Bootcamp Assistant itself before copying the WindowsSupport software to it:

Macbookpro-2:~ silvano$ diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage Macbook HD              499.4 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3

/dev/disk1 (internal, virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Macbook HD             +499.0 GB   disk1
                                 Logical Volume on disk0s2
                                 69E26A69-CF3B-4E39-B7F9-BC8154952589
                                 Unencrypted

/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *63.2 GB    disk2
   1:                 DOS_FAT_32 WININSTALL              63.2 GB    disk2s1

Below is the current state of my partitions. Partition 4 is where I am trying to install. I boot from EFI and it says it has an MBR, whereas he wants GPT.

Macbookpro-2:~ silvano$ diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage Macbook HD              451.4 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
   4:       Microsoft Basic Data                         48.0 GB    disk0s4

/dev/disk1 (internal, virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Macbook HD             +451.0 GB   disk1
                                 Logical Volume on disk0s2
                                 69E26A69-CF3B-4E39-B7F9-BC8154952589
                                 Unencrypted

/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *16.0 GB    disk2
   1:                 DOS_FAT_32 WININSTALL              16.0 GB    disk2s1

Any tips welcome.

MBP 2013, Sierra 10.12.6

Silvano

Answer 1

To change the drive partitioning to a pure GPT format, enter the following commands. The commands may not make any sense to you, but the volume format can change the type of partitioning.

sudo  diskutil  erasevolume  jhfs+  BootCamp  disk0s4
sudo  diskutil  erasevolume  FAT32  BOOTCAMP  disk0s4

From the description of your problem, below is what you need to do when you are asked about partitioning while installing Windows.

1. Select the partition labeled BOOTCAMP.
2. Click on the button labeled "Format". The BOOTCAMP label should disappear.
3. Proceed to install Windows.

You have assumed the Boot Camp Assistant application can NTFS format a partition. If fact, it can not. Instead, the partition is FAT32 formatted with the label BOOTCAMP. You must click on the Format button during the Windows installation to NTFS format the partition. This removes the BOOTCAMP label. Later, when the Boot Camp Support Software is installed, the NTFS partition will be labeled BOOTCAMP.

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To be clear, Windows installations on this model Mac must use the EFI boot method. This requires the installation drive to contain partition entries in only the GUID Partition Table (GPT). Both Windows and macOS (OS X) will only see the the GPT entries. Therefore, both Windows and macOS (OS X) with think the drive is GPT partitioned.

Answer 2

All that is way too involved. All you need to know is, when you get the error message, look at the options below the list box. One of the options is Format. Use it. You are now good to go.