How to create a Windows 10 (Build 10240) bootable USB drive by making your own clean install ISO today

Posted by Paul Braren on Jul 26 2015 (updated on Jul 28 2015) in
  • Windows
  • Productivity
  • JUL 28 2015 Update - breaking news

    This rough-around-the-edges article is intended for an IT Professional audience that already has an upgraded Windows 10 Preview Build 10240 (Pro), and knows their way around a BIOS boot order menu and the administrative command prompt. It also assumes a willingness to temporarily use some free third-party tools (7-zip gets installed, the other two are portable), along with an unsupported-by-Microsoft install method. It's all done at your own risk. That said, it sure seems to work just fine, as I've really just a pulled together and updated what Ed Bott, Paul Thurrott, and Andre Da Costa (MVP, Microsoft Community Moderator) have described.

    Installing from an 8GB or larger USB 3.0 flash drive using an ISO made with this method was smooth, and I simply chose to skip any prompts for license keys. Not sure how many days I'll have before it starts complaining that I'm not on an activated PC. I'm assuming we'll be able to provide a legitimate Windows 10 license key at a later date, presumably after the expected big Windows 10 launch on July 29th 2015. I cannot guarantee that will be the case. Seems somewhat likely, given what Paul Thurrott says here.

    [03:53pm EDT - added notes, if the particular PC you'll be doing this fresh install on was already activated under your Microsoft login, odds may be better that you'll be able to reactivate this 10240, but we can't know for sure. There is a chance you won't be able to activate it ever, requiring a rebuild, see also Richard Hay's tweet to Microsoft's Gabe Aul. This article isn't really about licensing, it's just about one way you can do fresh installs currently, since Microsoft has removed the Windows Insider downloads for this Technical Preview, and never provided a 10240 ISO, not even in MSDN. Things get even murkier when trying to think about how Windows 10 VMs made from this ISO will fare.].


    • A working copy of Windows 10 build 10240, since there's no watermark on your desktop, verify your build by pressing the Windows Key, type winver and hit enter
    • A Windows PC with USB 3.0 ports, and a USB 3.0 flash drive, to create the bootable media much faster. The ISO can be created with Windows 10 or Windows 8.1.


    1. 7-zip 9.20 64 bit

    2. ESD-Decrypter (post by MVP/Community Moderator, file is named esd-decrypter-wimlib-4.7z)

    3. Rufus 2.2 Portable (only needed if you want to make bootable install media from the ISO)

    Step-by-step creation of the ISO

    VERY ROUGH DRAFT, further refinement planned, video is best

    ESD Decryption just finished doing its thing.
    1. install 7-zip

    2. create a folder named c:/windows10staging

    3. right-click on esd-decrypter-wimlib-4.7z to extract it to c:/windows10staging

    4. copy (hidden by default) file C:\$Windows.~BT\Sources\Install.esd to c:/windows10staging
      (if you cannot see this file, turn on Folder views / Advanced settings, Hidden files and folders / Show hidden files, folder, and drives)
    Rufus just finished doing its thing.
    1. right-click on decrypt.cmd and choose Run as administrator

    2. select option 1 Create Full ISO with Standard install.wim

    3. even on an SSD, it will take at least 10 minutes to do all the hard work of creating the ISO named en_windows_10_pro_10240_x64_dvd.iso

    Step-by-step creation of the bootable USB 3.0 flash drive

    1. insert USB 3.0 media into the same PC where the ISO was just created

    2. launch Rufus

    3. use the DVD icon to choose en_windows_10_pro_10240_x64_dvd.iso (the ISO you just created)

    4. choose MBR partition scheme for BIOS or UEFI

    5. click Start

    6. when Rufus is done, close it, then eject the USB 3.0 flash drive

    Step-by-step video

    This 9 minute video will walk you right through the entire procedure

    See also at TinkerTry


    See also