I recently used this tool to successfully installed Windows 8.1 Pro. If you want to install windows 8.1 still you can select windows 8 Installer option it will work fine. Here is a Step By Step Guide to Fix Windows 7 USB/DVD Download Tool Not Valid ISO File Error By Using Ultra ISO Software So Follow the Instructions. Once you install it, Open the tool and from drop down you can select Windows 7 Installer or Windows 8 Installer. Microsoft released a USB DVD download tool that allows you to grab an ISO file from Microsofts own store and then put it onto a USB stick, but it wont let. This is working perfectly fine for all sort of Windows ISO including untouched and modified/customized. Just download the Universal USB Installer from below button and Install it.

Well there is very easy alternative for this. How To Fix Selected File Is Not A Valid Iso File Error Please select a valid ISO file and try again. So if you select any other modified ISO or customized ISO images then this error pops up that “The selected file is not a valid ISO file. Ever wondered why this error occur and how to fix it? Because Microsoft USB DVD tool works fine ONLY on untouched official ISO files of WIndows 7, Windows 8 or 8.1 versions. Well most of us may have encountered this error while using Microsoft USB DVD tool.

Not a valid iso file