Registry Location For File Extension Associations

ADezii 46 Reputation points

Can anyone provide the exact location in the System Registry where the Default Programs for File Associations are stored? Case in point, if I would want to know the Default Programs that will open *.rtf, *.pdf, *.txt, *.doc, etc. Querying the Registry is not a problem for me. I have looked at various locations and combinations of Keys/SubKeys, but nothing specifically points to the exact location. If I change the Default Program for *.txt from Notepad.exe to Word.exe, I need to see this in the Registry. My Current Platform is Windows 10.

Windows 10 Setup
Windows 10 Setup
Windows 10: A Microsoft operating system that runs on personal computers and tablets.Setup: The procedures involved in preparing a software program or application to operate within a computer or mobile device.
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  1. Dave Patrick 351.9K Reputation points MVP

    Something here may help. User settings override machine settings.

    --please don't forget to Accept as answer if the reply is helpful--

    Regards, Dave Patrick ....
    Microsoft Certified Professional
    Microsoft MVP [Windows Server] Datacenter Management

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees, and confers no rights.

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  1. ADezii 46 Reputation points

    Thank you DSPatrick for such a swift reply. You have actually isolated the problem for me which is:

    With Windows 10 you can’t manage file association settings through the Registry

    I need End Users to check for the Default Program for *.pdf on their PCs and I need to do this pro-grammatically. The only option as I see it, and as you have guided me, is to Export File Associations to an *.xlm File, then extract the Default Program associated with the .pdf Extension. This can be done by:

    Dism.exe /online /Export-DefaultAppAssociations:C:\PS\DefaultAssoc.xml

    This would normally not be a problem, except a new problem now arises as indicated below:

    Elevated Permissions are required to run DISM.

    Use an elevated commnd prompt to complete these tasks.

    Unless you indicate otherwise, there appears to be no resolution to this issue.

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  2. Dave Patrick 351.9K Reputation points MVP
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  3. ADezii 46 Reputation points

    Thanks DSPatrick, but it doesn't appear to be a viable option, at least to me. I can easily output File Associations using Dsim.exe at a Command Prompt to an *.xml file, search for the line with the .pdf extension, and see if Adobe Acrobat Reader is the Default Program (example posted below). The only problem is that I need to Run cmd.exe as Administrator in order to accomplish this.

    <Association Identifier=".pdf" ProgId="AcroExch.Document.DC" ApplicationName="Adobe Acrobat Reader DC" />

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