Build your own Windows 10 Bootcamp USB Installer

by: Loner T

Last modified: May 6, 2021 12:34 AM

9 57696 Last modified May 6, 2021 12:34 AM

Find a USB2 flash drive 8+Gb.

Note: If you use W10 1903 or later ISOs from Microsoft, the install.wim is larger than 4GiB, and will not fit on a FAT32 USB. Use exFAT format instead of FAT32.

Erase/Format it as MBR/FAT32.

Download
- Bootcamp 6 drivers from Apple to the root of the USB for W10. These can be downloaded using BC Assistant -> Action -> Download.
- Bootcamp 4/5 drivers from Apple to the root of the USB for W7/W8.1, as appropriate. You will also need to add the Bootcamp drivers to the USB as noted in step 11 of section Follow these steps if you downloaded version 5 of Windows Support Software in Install Windows 7 on your Mac using Boot Camp - Apple Support . These steps are valid for both W7/W8.1.
- The USB file structure look similar to

Copy the entire contents of your Windows ISO to this USB. This is your USB installer.

Note: There is some confusion whether the entire ISO is copied as a single file to a FAT-formatted device which does not support files larger 4GB. Mount the ISO by right-clicking on the ISO and choosing Open. Select all the individual files/folders in the Finder window and Copy (or Drag) them to the USB.

To create a partition manually which will be the designated Windows installation destination, create a FAT32 partition using Disk Utility.
Boot from the USB, and choose the FAT32 partition as destination and install Windows.
If you get a GPT vs MBR error, GPT Fdisk (https://sourceforge.net/projects/gptfdisk/) can be used to remove the Hybrid MBR.

A Protective MBR allows EFI Boot on Late 2013 or later Macs.A Hybrid MBR allows Windows in legacy BIOS mode using the Windows icon from the USB Installer on 2012-2014 Macs.

Warning: Do not use a USB Installer on 2011 or older Macs. These Macs do not properly support EFI Boot, even if Windows will install. The quickest check is either using msinfo32 or testing your Audio. If Audio does not work, you need to use a legacy BIOS installation.

If you see error messages which are similar to the following screens...

then please see Bootcamp install windows to black screen for a possible solution.