[How to] extract .SDC file from MSDNAA


Update Nov 10th 2009

If you still have the latest .sdc file of Windows 7 Professional and are unable to mount/extract it, you should stop trying as you can now obtain Windows 7 Professional ISO from the official retail website. Here is the link to obtain your Windows 7 image file

If you are like me downloading files from a source that’s end with .SDC file. How to extract it? First thing first, what is SDC file?

The .SDC file format is a Secure Download Cabinet file. It is an encrypted and compressed file format for Internet delivery of the products. The product executable that is downloaded from ELMS decrypts and extracts the product. If you have an SDC file on your hard drive after downloading a product, the process has failed. Delete the SDC and try again.

Note that this kind file will only exist when you download from ELMS encrypted MSNDAA site. I got it from my school SFU’s MSNDAA website. They have the newest Windows 7 Professional available to download both 64 bit and 32 bit. You can download from the website or burn your own DVD. However, when I choose to download it from their website, I always getting an error code: SDC00400

My installer returns an error SDC00400 – Unable to complete download what is wrong?
The SDC00400 – Unable to complete the download error is typically caused by:

  1. an error in the configuration of the download package, usually due to a bad hosting location
  2. no Internet connection found
  3. Internet connection lost
  4. a firewall or proxy server between the client station and hosting location, or
  5. insufficient disk space to download.

Which means if I want to have it working I need to wait and download it from the official way, which I doubt will fix the connection or anything to do with the list above. So I ended up going to this site that offers the exact same file from the official MSNDAA.

Because the file is encrypted you can’t use any tool you normally use to extract it. I found this guy who wrote a program that can decode the encryption and extract the file, though he didn’t write much instruction on how to use the command utility exactly.

Correction: When you download the file from MSNDAA there will be 2 separate .sdc files you need to combine them together (same as other files over MSNDAA)



Rename them to 1.sdc and 2.sdc for easy command line file name entry.

unpack sdc - [How to] extract .SDC file from MSDNAA

Here I renamed the file into 1.sdc and 2.sdc make the new file called 3.sdc (for easier command line use)

Next You need to unzip the “unpacksdc” first, and then navigate to the same directory as your newly combined sdc file.

Type: unpacksdc [space] [sdc file name] [space] [output directory] (don’t enter bracket and space when using the command line)

On the image above I extracted the file named “en_windows_7_professional_x64_dvd_X15-65805.sdc” to C:\Download directory. (or 3.sdc instead of the full name, since you’ve already combine them in the previous step)

The total unpacked size for en_windows_7_professional_x64_dvd_X15-65805 is 3149108KB and en_windows_7_professional_x86_dvd_x15-65804 is 2443256KB

Enjoy! That’s it. This works for any other sdc files.

Download the latest unpacksdc here.


As one of our readers pointed out that all the problems you might experience after late Aug are the result of the change Microsoft did on the encryption.The guy who wrote the sdc unpacker is currently working on the new version that will also includes a UI for general public easy use. However, since the new unpacker hasn’t released. You may want to find some other alternatives to download the ISO file. (usually your school should also provide the ISO image file for you to burn as well)

Once again, if you luckily got it working, great. But if not, maybe come back another time to check this post. I will update it accordingly.


  1. I tried using ur method for windows 7 professional from the MSDNAA site and using the version of unpacksdc that u suggested, but every time i get a message saying “file not sdc or format not supported”. I used the same program with the vista files and was able to unpack them (all from same MSDNAA site)

    Do u have any suggestions? Perhaps I am doing something wrong

    • Hi enyad, first there are few things need to be cleared. I did this method is because I getting the error code, won’t let me start download from the offical MSNDAA, later I found the site that offers the exact same file. So I downloaded from there.

      Now I only got .sdc file, so first is try to combine the twon into one sdc file. As I’ve mentioned use the command

      copy /b 1.sdc+2.sdc 3.sdc

      this will create and combine a new file

      using this newly created 3.sdc and put the unpacksdc command line utility on the same directory. Use the command line to navigate to the directory, and type “unpacksdc” follow with the 3.sdc and the new file location.

      let me know if you still have trouble doing this.

  2. MSDNA downloader made me crazy. I downloaded MSDNA windows 7 sdc file twice, but when it had to check crc it freezed. The unpacking sad its not a supported file format. So I realy hope, this way works. How can a Word famous company work like this? Shame on you Microsoft!

  3. This has been very helpful, thank you. Now with the unpacked file, can I write it to a DVD to use for installing or what file type is it?

    Besides this I just ran into some unhandled exceptions which I will post in a reply to this, I could use some help.

  4. For all getting the “checking file crc..” problem in the downloader and for which the above does not work read below.

    For me the above did not work(I was getting file not sdc error). So i downloaded the files mentioned above, combined them in 1 file. Renamed it to en_windows_7_professional_x64_dvd_X15-65805.01.sdc and moved it to the MSDNAA downloader folder. I had a file named the same way there, so i replaced it. Then I started the downloader again and clicked “Resume”. This time the downloader unpack it without a problem. I had a iso with the correct SHA1 hash 50127304441A793EE51B3F501289F6599A559E9F.

    Thats it.
    If you have any questions ask.

  5. Hello,
    i have downed it but with unpacking 3.sdc
    get is this in cmd.exe

    UnpackSDC 1.1 imagi
    Usage: UnpackSDC [SdcFile] [OutputDir]
    SdcFile – file to unpack
    OutputDir – file to unpack
    skiprc – when specified, crc check will be skipped

    Can anyone help me to fix this problem?
    Btw, im XP user, i hope it can be unpacked on XP either. Please help me! Thank you.

  6. I downloaded it. There is only one . Sdc file on the ecamedy for me. When I open the unpack extraction it just open with flash screen and disappears.
    And then I try it in windows cmd.
    Am I doing the right thing?

    Everytime I do it it says unpacksdc is not valid internal or external……
    Download the file 4 times. It wouldn’t unapack by it self.

  7. Uh, don't know if anyone has mentioned this already (sorry if they have), but when you download the Windows 7 thing from the MSDNAA website, you need to be connected to the 'local intranet' of whichever school you go to. You can't download it from home or over the wireless network available at school.

    • I am using windows vista. After combining 1.sdc and 2.sdc when I try use unpackdsc command, I receive ” 'unpackdsc' is not recognized az internal or external command”!

  8. hii Jonathan i downloaded windows7.sdc and unpack with unpacksdc but then there is not windows7.iso like yours there is always windows7.sdc again after unpack with unpacksdc sorry for my bad english lol :p where is the problem?

  9. the people who are getting error or manual unpacking of SDC file here is a way i personaly discover
    first in command prompt combine 2 sdc files
    e.g c:downloadcopy b 1.sdc+2.sdc 3.sdc
    1 file sucessfuly copied

    now unpack the file using MSDNAA software give him the path where u have copied file 3.sdc and again rename the 3.sdc file to original name
    e.g i’ve downloaded win7 pro x86 so its original name is
    after renaming give MSDNAA software the path where this file resides it will check for CRC the make en_windows_7_professional_x86_dvd_x15-65804.01.iso file
    if any problem mail me at [email protected] with subject WIN 7 UNPACKING ERROR

  10. Need help. I have a .sdc file of Win2000. I need this file which is in English so I can set the old schools PIII server tower they have. But I seem to run into a wall here. The .sdc unpacker won’t run. The Win2000 file is only 1. So what am I missing in getting this file unpacked?

    As soon as the unpacker starts to work I get an error message and that it must shut down. I’m using the unpackersdc11 app.

    Any help would be nice.

  11. Just to clarify, does this program still work?
    Every time I attempt to use it I’ve been unable to make any progress. I’m getting the error: “This file is not SDC file or this format is not supported.”
    Any help is greatly appreciated.

  12. it gives an error msg
    the application failed to initialize properly (0xc0000135) click ok to terminate the application

    plz help

    • that’s right. as long as you have the key, and it matches to the version of ISO you are going to download it will be ok


Please enter your comment!
Please enter your name here