Windows 10: .iso extension missing from settings/choose default apps by file type

This ties partly into my other issue of not being able to mount ISO files in windows explorer. I am getting no luck on fixing that separate issue, so maybe if i tackle it at a different angle, the other problem could be solved as well. Please do not move this issue to Virtualization.



The Issue

Basically, in my "Choose default apps by file type" settings window, the .iso extension is missing. I am running Windows 10 Home Version 1809



In the past, it was there, and also in the past, I was able to mount .iso files by right clicking, and selecting "mount". The option to mount is still there;





But gives me this error;





(this is part of my secondary issue being taken care of in another thread (hopefully)) so please don't move this thread to virtualization.

What I want:

I want the .iso extension back in my list of extensions in my settings --> default apps--> choose default apps by file type window.


Things I have tried;

• 1) Going to Settings - Indexing Options
  2) Advanced button
  3) File Types tab
  4) Add New Extension to List box, type in extension, (without a period) in this case "iso"
  5) Click OK and Close
• Right clicking any .iso file, and selecting "open with", then selecting "choose another app", and then selecting "Windows Explorer".
• Right clicking any .iso file, selecting "Properties", then selecting the "Change" button under "opens with" and selecting "Windows Explorer".
• Restoring the default Windows file extension through registry fix detailed here with OPTION TWO and selecting the .iso reg file, adding it to my registry, and restarting my pc.
• I created a "fake" extension named .isotest. It successfully appeared in the settings menu(see picture above)
• Ran "DISM /Online /Cleanup-Image /RestoreHealth" in elevated cmd prompt and then "sfc /scannow" in an elevated command prompt. No issues were found.

In the registry, it shows that iso files are opened with Windows.IsoFile. Looking under the reg key, I cannot tell if anything is incorrect. Below are the reg keys associated with Windows.IsoFile and the .iso key in Computer\HKEY_CLASSES_ROOT\















I'm not sure what else to do aside from formatting my pc which I really don't want to do for this issue. Help is greatly appreciated. Please read the whole post before suggesting things please.

Thanks.

:)

 

How to set a default app for extensions?

Hi Tyler,

Which app are you trying to set for .res extension?

Please try to check the app you are trying to set. Is it feasible with .res extension?

I suggest performing the steps below and check if it fixes the problem.

Go to Setting - Apps - Click on Default apps - Click on Choose default apps by file type.

On the left, search for .res extension

Across .res extension, tap on Choose a default

Try browsing for the app.

 

Cant set the default app for extensions

Hi Alex,

Thank you for writing to Microsoft Community Forums.

We'd like to get more information regarding the issue.

1. May I know which app you are trying to set for
   .res extension?
   
2. Could you check the app you are trying to set, if it is feasible with
   .res extension?
   

You may follow the steps mentioned below and check if it helps.

1. Go to Setting >
   Apps.
   
2. Click on Default apps.
   
3. Click on Choose default apps by file type.
   
4. Look for .res extension on the left pane.
   
5. Across .res extension, click on
   Choose a default.
   
6. Try browsing for the app.
   

Hope it helps.

Manjunath H

Microsoft Community - Moderator

 

choose default apps by file type

When going to Settings / Apps / Default apps , I am unable to choose default apps by file type, ie the file type boxes ( .bmp .gif etc ) greyed out "Choose a default" missing. This means every time I click a bmp or gif file I have to select what app
to open it with .