Unable to Change Default Program Extension on Windows 7 / 8 / 10

Today, I’m going to show you a way out, if you ever face a situation, where you are unable to change the default program extension in Windows 10 / 8 / 7. I was helping out a client of mine. His operating system had somehow changed the default program extension to a different program; i.e. the file was supposed to open with Outlook – but instead it change into Notepad.

Unable to Change Default Program Extension

When I tried to change it back to Outlook under Properties of that file the change option was grayed out


So I tried to right-click on the file and clicked on “Open With” dialog box, because there you have a change box “Always use the selected program to open this kind of file”.

But strangely that check box was grayed out, as well. When I select Outlook, it opens fine. But I was just unable to set it as the default option.

So I went to Control Panel\All Control Panel Items\Default Programs\Set Associations and tried to change it there; but sadly I was again unable to. I was totally stumped because the UAC was turned off, the user is a Windows administrator – so there was no reason for the option to be disabled.

That’s when I remembered that there is an option in Windows registry, where you can change it. So I opened the registry and navigated to the following key:


Here you have to find your extension under a key called “UserChoice”.

What this registry key does, is if you change the Default file extension, Windows creates this key and adds the value there.

On the Right hand side you’ll seestring value “Progid” under that value you’ll see the current program that is associated with it. So I tried to change that value but it gave me an error: Cannot edit Progid.


Now I realized what was wrong! For some reason, that specific registry key doesn’t have permission to change the file extension, and that was the reason why those options were grayed out for me. So I took ownership for the parent key  and inherited the permission.


Now I could delete the “UserChoice” key. Once I deleted it and I rebooted the system. And voilà – now I got this window!


Once I selected the correct program I made it as default and it stayed.

Hope this becomes helpful for someone who runs into a similar problem.

These links may also interest you:

  1. File Association Fixer for Windows 7
  2. Default Programs Editor for Windows 7
  3. Remove unwanted programs from Recommended Programs List in the Open With box
  4. How to dissociate File Types in Windows 7 and Vista.
Posted by on , in Category Windows with Tags
Shyam aka “Captain Jack” is a Microsoft MVP alumnus and a Windows Enthusiast with an interest in Advanced Windows troubleshooting. Suggestions made and opinions expressed by him here are his personal one's and not of his current employers. He blogs at captaindbg.com.
  • Gdghgfgjy Ggjffv

    Thanks! I was having a problem where all .theme files opened up with explorer.exe. I am going to change it to shell32.dll after reboot.

  • Mathman47

    Wow, nice job. I hope I never have this problem, but if I ever do, at least I know what to do, that is if I can find this article again!

    Thanks for sharing your experience.

  • Thankful noob

    Thanks for this! I somehow associated my video files to open with windows explorer and it wouldn’t let me change it.

    Deleting that registry key did the trick though, so thanks again!

  • Harmanjaidka

    sir all the program of my system have been defaulted to window media center.. if i try to open any program in my system its opened by w.media center. like opera, Google chrome, system restore, please help me out

  • http://www.facebook.com/harmanjaidka Harman Jaidka

    hey how could i able to delete that registry key..??

    all the program of my system have been defaulted to window media center.. if i try to open any program in my system its opened by w.media center. like opera, Google chrome, system restore, please help me out

  • http://www.facebook.com/harmanjaidka Harman Jaidka

    not even able to open regedit. media center is opening it on behalf of any other thing

  • daniel kongle

    this happens to me with all programs in default programs list… what do i do then?

  • Chlump

    You did it! All the Windows forums couldn’t help me at all. Extensions were ghosted out in all the default programs and file associations tools, or when I’d change the default program to open the extension, nothing would work. I then found this permissions problem. This was happening with .WAV files. Unassociated the extension, and re-associated, and it finally works!

  • R Schroder

    Hats off to ShyamS@TWC for this most useful ‘unable to change default program’ howto guide. Took me straight to the solution at this end. Good show.

  • Vipi

    Just delete the UserChoice and set the default again by double clicking the file.

  • usama

    my computer is also opening the registry with notepad plz tell me how to open it

  • http://www.thewindowsclub.com Anand Khanse
  • notTheSame

    I don’t have a “User Choice” under that key.

  • adt

    Amazing, worked like a charm! Thank you!!!

  • alex

    THANK YOU, THANK YOU, THANK YOU, worked great!

  • Erica

    Oh my gosh I spent HOURS trying to fix this, sooo frustrating and this solution worked! I am so nervous about working with registry keys but the backup and system restore point ideas gave me the confidence I needed to try this out and it worked like a bomb! THANK YOU SOOO MUCH!!!!!

  • Hammad Mubeen

    It is good thing, I had same problem but now solved. I made one change at FileExts… I simply found the extension type that was creating problem and deleted its complete value from registry. Next time I opened that program without restarting system and problem was solved.


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