This post explains why the Windows 7 USB/DVD Download Tool (WUDT) is unable to copy the install files to the USB drive in some cases. The tool allows you to create a copy of your Windows 7 ISO file on a USB flash drive.
Latest posts by Michael Pietroforte (see all)

Update: If you have problems Windows 7 USB/DVD Download Tool you can try the free alternative Rufus. The most powerful tool for creating a bootable Windows setup flash drive is WinSetupFromUSB.

You might have heard of the stir that Microsoft's Windows 7 USB/DVD Download Tool (WUDT) caused last year when some Open Source watchmen recognized that the tool contained code that violated the GPL. Microsoft was then "forced" to release WUDT under GPLv2. Considering the upset in the media about this incident, I expected a luxurious tool that comes with lots of customization features. I was somewhat disappointed to discover it does nothing else but copy the contents of a Windows 7 install DVD to a USB stick and make it bootable.

Windows-7-USB-DVD-Download Tool-WUDT

The funny thing is that WUDT even failed to perform this simple task with my no-name USB stick. This message was the only thing that the Open Source tool could do for me:

We were unable to copy your files. Please check your USB device and the selected ISO file and try again.

At least, my cheap stick wasn't the cause because everything worked perfectly when I manually did the job (hopefully without violating any Open Source laws). So, I thought, I would write this post for those who might run into the same problems and think they need to buy another USB stick. After all, this is Microsoft software and there are not many options to integrate bugs in such a simple tool.

Anyway, here is what you have to do. Launch a command prompt with admin rights and run the diskpart tool. Note: Before you run these commands read the warning below!

list disk
select disk #
create partition primary
select partition 1
format quick fs=fat32

The "list disk" command will show you the connected drives and with "select disk", you can choose your USB stick.

WARNING: Be careful to select the right drive or else your day won't have a happy end because if you select the wrong drive you will lose all your data on this drive!

The crucial step here is the "clean" command. It overwrites the MBR and the partition table (thereby, deleting everything on the stick). My guess is that WUDT misses this step and only formats the flash drive. It appears my memory stick had some odd partitions (which is not uncommon). When I tried WUDT again with this prepared stick, the Open Source tool mastered its task without further murmur.

By the way, this is also the reason why you shouldn't use the Windows Disk Management applet to prepare the USB stick. This GUI doesn't offer a clean command.

After you prepare the stick, you have to copy the contents of your Windows 7 DVD to the thumb drive, and you are done. If you only have an ISO file, you can use Virtual CloneDrive to mount the Windows 7 install DVD first.

Instead of formatting the partition with FAT32, you can also use NTFS (like WUDT does), but then you need an extra step to make the drive bootable:

Bootsect.exe /nt60 X:

"X:" is the drive letter of your USB stick. Bootsect.exe can be found on the Windows 7 DVD in the boot folder. However, I can't really recommend using NTFS. My USB stick, at least, appeared to be slower with NTFS.

  1. Avatar
    hoho 11 years ago

    thanks a lot 🙂

  2. Avatar
    Kroco 11 years ago

    Really thanks bro it worked really well you save me a few hours in web =)

  3. Avatar
    rm 11 years ago

    Excellent! I thought it was vmware causing issues at first!

    but this now work in virtual machines too!

  4. Avatar
    bradford 11 years ago

    Thanks! This fixed an issue for me trying to get Windows Server 2012 on a bootable USB drive.

  5. Avatar
    Anonymous Coward 11 years ago

    3 years later and this is still a useful tip. Thanks!

  6. Avatar
    George H 10 years ago

    I guess I am one of the unlucky ones. I tried your diskpart steps, I disabled my virus checker, I installed the HP formatter (discussed in the comments) and I even installed Rufus. Nothing works.

    Nothing crazy about the ISO. It comes from MSDN downloads. I even downloaded it twice.

  7. Avatar
    Abhishek Kumar SIngh 10 years ago

    HI, I have done the booting of computer before with the same usb drive. Now i am having this error problem and i have done all the step you have written. Still, it does not work for me. Please help me.

  8. Avatar
    Abhishek kumar singh 10 years ago

    Any one trying to copy .iso file to USB and having problem then try to disable the antivirus which helped me to copy. sshhh at last I could copy.

  9. Avatar
    George H 10 years ago

    Here’s an update to my post above. The WUDT kept failing with 99% completed. After giving up, I happened to notice all of the files were happily waiting on the USB drive. Just for fun, I ran the setup to see what would happen. Setup completed successfully!

  10. Avatar

    George, yeah never trust an error message. Sometimes the message is the error. 😉

  11. Avatar
    Samy 10 years ago

    iT’s Done, Work Perfectly
    Thank You So Much


  12. Avatar
    Samih Qabaha 10 years ago

    Thanks too much 🙂

  13. Avatar
    MWH 10 years ago

    thank you very much.

  14. Avatar
    Chris 10 years ago

    Thanks Michael, works like a charm!

  15. Avatar
    Chris 10 years ago

    Thanks dawg. Worked a treat!

  16. Avatar
    wibble 10 years ago

    That fixed it – wouldn’t work with a USB3 stick, never had a problem before. Many thanks 🙂

  17. Avatar
    Eduardo 10 years ago

    TKS!! Work for me!!

  18. Avatar
    Tim 10 years ago

    Nice it works great! Thinking my usb device sucks, but this is the solution!

  19. Avatar
    Matt 10 years ago

    Thanks! This did the trick… you’d think Microsoft would just make a tool that actually works to let you install their software.

  20. Avatar
    Justin 10 years ago

    Thanks a lot Michael! This worked perfectly. I had the same problem as the first poster Luke, I had used a Kingston G2 flash drive several times with WUDT but today it just would not work. After following your instructions it worked the first time.

  21. Avatar
    Scott 10 years ago

    Works like a champ – thanks!!!

  22. Avatar
    Edgar 10 years ago

    It worked, thanks !

  23. Avatar
    yasamoka 10 years ago

    Thanks! This worked wonderfully!

  24. Avatar
    andrea 10 years ago

    THANK YOU, THANK YOU, THANK YOU!! I could say it a MILLION time over THANK YOU!

  25. Avatar
    ravi 10 years ago

    If WUDT doesn’t work then check this,

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