Unable to change Default Program Extension on Windows 11/10

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Today, I'm going to show y'all a mode out, if you e'er face a situation, where you cannot or are unable to change the default program extension in Windows 11/x/viii/vii. I was helping out a client of mine. His operating system had somehow changed the default programme extension to a unlike program; i.e. the file was supposed to open up with Outlook – only instead, it changed into Notepad.

Unable to change Default Plan Extension

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

And so I tried to right-click on the file and clicked on "Open With" dialog box, considering at that place you accept a alter box "E'er use the selected program to open this kind of file".

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

So I went to Command Console\All Control Panel Items\Default Programs\Set Associations and tried to change information technology at that place, but sadly I was once again unable to. I was totally stumped because the UAC was turned off, the user is a Windows administrator – and so there was no reason for the choice to exist disabled.

That's when I remembered that there is an option in the Windows registry, where y'all can change information technology. So I opened the registry and navigated to the post-obit cardinal:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts

Here you have to discover your extension under a key chosen "UserChoice".

What this registry key does, is if yous change the Default file extension, Windows creates this key and adds the value at that place.

On the correct-hand side you lot'll meet a string value " Progid" under that value you'll come across the current program that is associated with it. So I tried to alter that value but it gave me an error: Cannot edit Progid.

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

At present I could delete the "UserChoice" key. Once I deleted it and I rebooted the organisation. And voilà – now I got this window!

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

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

These links may likewise interest you:

File Association Fixer for Windows
Remove unwanted programs from Recommended Programs Listing in the Open up With box
How to dissociate File Types in Windows.

Shyam aka "Captain Jack" is a Microsoft MVP alumnus and a Windows Enthusiast with an involvement in Advanced Windows troubleshooting. Suggestions made and opinions expressed by him hither are his personal one's and not of his current employers. He blogs at captaindbg.com.