Hi,

the install.wim of Windows 10 iso Images which contains multiple OS Versions is usually greater then magic 4GB broder.

Therefore it is not possible to copy this file to an FAT32 formated USB Stick because FAT32 has a file size limit of 4GB.

A way to shrink the wim file is to extract only the OS Version you want to install. dism can do this since Windows 8. Copy the install.wim file to your harddisk, i.e. D:\temp and see which Windows Versions are included

D:\Temp> dir D:\Temp\install.wim
03.08.2017  22:57     4.810.578.598 install.wim
D:\Temp> dism /Get-WIMinfo /wimfile:install.wim

Deployment Image Servicing and Management tool
Version: 6.3.9600.17031

Details for image : install.wim

Index : 1
Name : Windows 10 Pro
Description : Windows 10 Pro
Size : 15.870.553.953 bytes

Index : 2
Name : Windows 10 Home
Description : Windows 10 Home
Size : 15.688.600.726 bytes

Then export the OS Version to a new wim file and set maximum compression. Let use assume Windows 10 Professional which is Index 1:

D:\Temp> dism /Export-image /SourceImageFile:install.wim /SourceIndex:1 /DestinationImageFile:install-new.wim /DestinationName:"Windows 10 Pro" /compress:max
Exporting image
[==========================100.0%==========================]
D:\Temp> dir install-new.wim
03.08.2017  23:08     4.095.320.725 install-new.wim

Now the size does not break the 4GB size limit and can transferred to an USB Stick

Michael