How to Associate an UNLISTED file extension to a Windows app from the Microsoft store with the Registry Editor

-{This procedure will only work if the app already has at least one other file extension Associated to it}-


So you want to associate a file extension to a Windows app but the app doesn't show up in the "open with" dialog and the extension isn't listed in the default programs.


It's time for the big-boy program The Registry Editor.
(Abandon hope all ye who enter here and other registry editor warnings)


(As an example extension I'm going to use the last one I was added .Admx and you'll need the extension of a file type already associated with the desired app. for me the app was "Code Writer" and the extension already Associated to it was ".XML")


first we launched the registry editor. Use "Windows key" + R then type regedit and press enter (got mine pinned to the taskbar)
Once open highlight the first item in the left hand section "Computer" then pull up the "Find" box with Ctrl + F and type in the known file extension with the DOT (example .xml) and it should bring you to a key (remember left side=keys and right side=sub-keys)
A key labeled just that .xml (if the key found is anything other than dot and the file extension letters you did it wrong and most likely didn't highlight computer first).


Now right click on that key .xml and click export to save the key to a .reg (the name of the saved file and location doesn't matter as long as you remember it)
We are done with the registry editor you can close it.
Now we're going to edit that saved file using Notepad so go ahead and launch Notepad.


Once in Notepad click file on the menu bar and go to open change the drop down that says "Text Documents" to "All files" then navigate to the location where you saved the .reg file highlight it and click open.


There's not that much to this file or the change to be made. All you have to do is replace each instance that has the original extension .XML and XML (With and Without the DOT) with the new extension you want the app to open so .xml gets replaced with .admx and xml gets replaced with admx once you have replaced each instance save it by clicking file in the menu then save. and close notepad.


Now open file explorer and navigate to the file you just saved and open it, Click YES on the warning message then OK on what should be a success message.


This shouldn't even require a restart, But most people when explaining registry procedures would tell you to restart so sure restart your machine.


and That's It! ( kind of anti-climatic right, I mean your computer didn't explode or anything)


I'm pretty sure the first comment going to be from one of the higher ups with the the whole registry editing warning routine that's why I didn't really do it.


Anyway Peace.

File associations are harder to change in W11, because there's a security hash to prevent malware from stealing control. This is why some apps can no longer switch file associations to themselves.

SetUserFTA is a command-line tool which solves this problem. This might be easier than regedit voodoo.

It's pretty easy it's actually does work quite well I've been doing it like the for a while now. best way to do that I found and without having to download more stuff to your machine. Associating a file extension shouldn't require more apps and programs, but at the same time shouldn't require this method either.

The point is you can bulk update FTA's w/o manual regedit which seems more error prone. If you wanted to promote your method, why not write a wrapper script to do the work? Remember, not everyone is technical.

Wait, did you call it Voodoo? Is everyone really that afraid of the registry editor? Microsoft got into your guys heads.
Don't let them do that. The way things are going I see a future where the registry editor is the only thing left that can customize or change windows the way you want it to run . but everyone will be too afraid to use it.
Don't buy into the Microsoft scare tactic.
Yes it has the ability to mess things up so dose of things. (which kind of shows you how useless the trust installer is)
But don't you think it would be better to educate rather than scare people away from it.
I sure do.

But you should never go into it and just start throwing random switches, that's my job. I got that covered

I guess when it comes to the errors with manually editing. it would be all in how well you trust yourself and how familiar you are with the registry structure. over letting some unknown developer make changes for you. because really any program is just another human between you and the registry. Code doesn't just write itself. this is why you see with new builds multiple people having the same issue because that one developer messed up and now it's affecting everybody. Me I feel more comfortable doing it myself. But this is becoming an unheard of thought and it's worrying

Yes of course it has the power to turn Windows into a pile of unusable code. it's not something to be played with it's a tool and tools can injure. it's why we learn how to use them properly and we don't go around making people afraid to utilize them.

If Microsoft or anybody where to effectively teach people the basic fundamentals of the registry structure and how it functions we'd start to see a lot less errors when it comes to manual editing. and as people discovered new keys buried within the registry we'd also find a lot more system functionality and cool tips flying around.

it take very little time to figure it out and understand windows, and the way it actually functions and really have control of it. you know that scene in The Matrix when Neo figures he is the one and he's able to stop agent Microsoft... I mean "Smith's" bullets. Enlightened and Unstoppable. is the Best way to describe it. and It's not that hard to learn how to not only navigate but also start judging for yourself what keys can and can't be changed safely.

but the idea of a ton of user who know how to utilize the registry editor properly and to losing there grip on that information. doesn't sit too well with Microsoft, because then anything they changed the user doesn't agree with could easily be undone. Hell I wouldn't like my own weapons use against me either. So rather than teach it they demonize it.

So don't join that cause its basically telling everyone to take there best asset and tool in Windows and throw it in the trash.

The registry and registry editor are not something to fear they're not something you should avoid they are something you should learn about the answers to everything are in the registry