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
    Luke 14 years ago

    Thanks for posting this Michael.

    I used the WUDT countless times on the same Kingston G2 stick, until one time it decided not to restore – strange.

    Anyway, it’s working again so thanks again!

  2. Avatar

    That’s interesting. I thought it is only a problem with unprepared USB drives. Seems there are some other bus in WUDT.

  3. Avatar
    Thew 14 years ago

    This worked to correct the problem for me. I had previously used my USB drive to boot an Apple Mac X OS and clearly it had some residual MBRs that needed to be cleaned.

  4. Avatar
    Finn 14 years ago

    Thanks Michael!

    That clean command did the trick. U just saved me a whole day of fiddeling arround!

  5. Avatar
    Anthony 14 years ago

    I’ve been struggling with this for a while. This post cleared it right up. Many thanks!

  6. Avatar
    Terry Walsh 14 years ago

    Fantastic workaround – a big thank you.

  7. Avatar
    hans 13 years ago

    thanks, it works! 🙂

  8. Avatar
    Adrian 13 years ago

    Nice one! Thanks very much, bit of a head scratcher!

  9. Avatar
    Rene Treffer 13 years ago

    I recently had the same problem with this MS tool, The solution was quite simple: disable Avira (free antivirus tool)! It turns out that the antivirus software detects malicious activities on the usb device (surprise, we are trying to make it bootable & copy stuff like autorun.inf!).

    So if you see this “can’t copy files”, try to disable your antivirus software!

  10. Avatar
    shanon 13 years ago

    thanks very much — i was totally stuck and this worked great.

  11. Avatar
    Sebastian Ortiz 13 years ago

    The problem resides in the partition table format.

    WUDT need a ms-dos partition table format, some cheap usb sticks don’t have a partition table, o some special operations like dd an debian image to the sticks erases that partitions.

    My solution is open gparted (or any partition editor) and create a ms-dos partition table on the stick.

    After that WUDT will work perfect.

  12. Avatar
    User5001 13 years ago

    Thanks 🙂

  13. Avatar
    Yogesh 13 years ago

    diskpart command with clean did the job
    thanks, it really works!

  14. Avatar
    Leandro 13 years ago

    Great post, thank you very much!
    Worked fine!

  15. Avatar
    dimaudi 13 years ago

    big thanks, it’s helpfull

  16. Avatar
    Benjamin 13 years ago

    Thanks Michael, your post solved the problem for me.

  17. Avatar
    Korean 13 years ago

    Diskpart doesn’t work well in xp.
    Because usb drives don’t seem when typing “list disk” at XP.
    They will be able to seem at least Vista.

  18. Avatar
    mihai 13 years ago

    Thank you for sharing. Microsoft tool is annoying….your steps did the clean install from usb stick quick and easy.

    Thanks again for helping me getting out from nowhere

  19. Avatar
    dome 13 years ago

    Thanks a lot! this is was so helpful!!

  20. Avatar
    caswell 13 years ago

    I’m not the most computer literate. Is there an idiot’s guide for the command prompt? Or at least for this process?

  21. Avatar
    caswell 13 years ago

    Nevermind. Trial and error prevails! (And I didn’t blow up my computer!)

  22. Avatar
    Onecar 13 years ago

    Much appreciated, have been experiencing this kind of strange behaviour. Anyways it works flawlessly for me now, thanks a lot for your advice 😉

  23. Avatar
    cleison 13 years ago


  24. Avatar
    imperator 13 years ago

    nice ware…
    but something wrong with my usb device after using this software.
    my computer did not recognize my usb device anymore.
    can anyone help me?

  25. Avatar
    krky 13 years ago

    Good Work guy !!!
    work pefectly !

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