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Create Windows 10 installer USB stick on macOS Catalina

Today my Windows 10 bricked itself after I enabled Hyper-V, I had no choice but to reinstall it. I only had my Macbook to create the USB stick. Here’s how.

First of all, find out which device is your USB stick:

$ diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *251.0 GB   disk0
   1:                        EFI EFI                     314.6 MB   disk0s1
   2:                 Apple_APFS Container disk1         185.0 GB   disk0s2
   3:       Microsoft Basic Data BOOTCAMP                65.7 GB    disk0s3

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +185.0 GB   disk1
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD            11.1 GB    disk1s1
   2:                APFS Volume Preboot                 104.4 MB   disk1s2
   3:                APFS Volume Recovery                1.0 GB     disk1s3
   4:                APFS Volume VM                      4.3 GB     disk1s4
   5:                APFS Volume Macintosh HD - Data     158.7 GB   disk1s5

/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *63.3 GB    disk2
   1:                 DOS_FAT_32 WIN10                   63.3 GB    disk2s1

/dev/disk3 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            CCCOMA_X64FRE_EN-US... +5.4 GB     disk3

Here it is /dev/disk3. Erase the device with

$ diskutil eraseDisk MS-DOS WIN10 MBR /dev/disk3

Next go to to get the installer ISO file. After that mount the ISO:

$ hdiutil mount ~/Downloads/Win10_1909_English_x64.iso

Now copy the files from the ISO to our USB stick, but not the oversized install.wim:

$ rsync -avh --progress --exclude=sources/install.wim /Volumes/CCCOMA_X64FRE_EN-US_DV9/ /Volumes/WIN10

Next up we’ll need to install wimlib, a tool that will help us manipulate .wim files through Homebrew. If you haven’t installed that already (how dare you!):

$ /bin/bash -c "$(curl -fsSL"

Then we can install wimlib:

$ brew install wimlib

Now split the oversized install.wim and save the files to USB stick:

$ wimlib-imagex split /Volumes/CCCOMA_X64FRE_EN-US_DV9/sources/install.wim /Volumes/WIN10/sources/install.swm 4000

Finally we can eject the USB stick with:

$ hdiutil eject /dev/disk2

Now pull off your USB stick, plug it to your PC and boot it up to recover your machine! Good luck.