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. Marcio Junior 9 years ago

    Thank you !!! Worked.

  2. Kyel Calland 9 years ago

    Cheers buddy saved me a lot of time and hassle, I owe you a beer!

  3. Chase 9 years ago

    It worked, finally something does!!!!!
    Now I can reinstall Win7, then I hopefully won’t get the bootstrapper error message when trying to load MS Office 2013.
    A Win 7 reinstall, is my last resort after reg fixes and uninstalls failed to allow a successful Office 2013 install.
    At this point without a disc, I was super frustrated when I couldn’t save to the USB, but am happy that someone knows what they are doing and is willing to help others.

  4. Mike G 9 years ago

    Great fix. I was re-using a USB that was previously used for Xbox save games; apparently more residual data/settings that could not be wiped.

    One tip: run everything as admin mode for this.

  5. ftouhi 9 years ago

    iT’s Done, Work Perfectly
    Thank You So Much

  6. w 9 years ago

    My flash drive and ISO were too large for FAT32, so I input fs=ntfs instead. Win7 tool is working fine now.

  7. Sujay 9 years ago

    It did not work for me. I am trying to create a bootable USB drive. I followed disk part steps and then tried WUDT. It again gave the same error. WUDT still try to format.

    Can I do something manually instead of using WUDT?


  8. Sujay, you can try Rufus. I also wouldn’t rule out that your USB stick is broken.

  9. Me 9 years ago

    Worked brilliantly thx!

  10. monkon 9 years ago

    It works. Thank you so much =)

  11. Mars 9 years ago

    I’m had the same Kingston DataTraveler 100 G3 8GB.

    After doing the diskpart commands in an elevated command prompt I successfully copied my ISO file using the Windows 7 USB/DVD Download Tool.

    Thanks for sharing this info.
    Greetings from Mars

  12. Kyle 8 years ago

    Just followed this and worked perfect. Like someone posted above, I used the flash drive to boot a Mac OS X. Reason it doesn’t work properly after using it to boot Mac OS X is that Mac drives use GPT (GUID Partition Table) instead of the standard MBR.

  13. Hristijan 8 years ago

    Thanks for the great post! It worked fine!

  14. Oggemista 8 years ago

    Thx but this doesn’t work for me because the diskpart utility tool wont “see” my USB removeable flash drive I get to “list disk” and only the combined space of the 2 internal HDD’s are showing but If I use list volume then all 3 drives show

    I am using windows xp professional, is this the core of the problem?

  15. zydmeister 8 years ago

    works like a charm!!! 😀 😀 😀

  16. shankar 8 years ago

    Thank you so much.

  17. Jordan 8 years ago

    Worked perfect. Thanks so much!

  18. Navaneeth 8 years ago

    Hi Mike,

    I did everything which you ve mentioned. But still its showing the same error. Is there any other things which has to be modified before starting the process.

    Please help me with this as I ve done this many times and going mad.

  19. MECV 8 years ago

    After you prepare the stick with the steps provided, you have to copy and past the contents of your Windows 7 DVD to the thumb drive, and you are done.

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