Set Firefox default browser by gpo

Question

Hi guys!
I use file association gpo to set some default apps in Windows 10.

From some point to now, set Firefox as default browser only work in our windows (20H2) deployed image ( with Acronis). If we use the defaul windows preinstalled doesn't work (whichever vendor).

I think that the problem is on exporting the default app associations due on my image the FF shows as: ProgId="FirefoxHTML" and on presintalled is:
ProgId="FirefoxHTML-E7CF176E110C211B" note that the alphanumerical string could be differ on others preinstalled windows.

The Firefox is the same in all windows and is the ESR distribution (I keep it up to date by scripting).

Here is the full file association that get with my image when run "Dism.exe /online /Export-DefaultAppAssociations:C:\PS\DefaultAssoc.xml":

<?xml version="1.0" encoding="UTF-8"?>
<DefaultAssociations>
  <Association Identifier=".pdf" ProgId="Acrobat.Document.11" ApplicationName="Adobe Acrobat" />
  <Association Identifier=".htm" ProgId="FirefoxHTML" ApplicationName="Firefox" />
  <Association Identifier=".html" ProgId="FirefoxHTML" ApplicationName="Firefox" />
  <Association Identifier=".url" ProgId="IE.AssocFile.URL" ApplicationName="Internet Browser" />
  <Association Identifier=".website" ProgId="IE.AssocFile.WEBSITE" ApplicationName="Internet Explorer" />
  <Association Identifier="http" ProgId="FirefoxURL" ApplicationName="Firefox" />
  <Association Identifier="https" ProgId="FirefoxURL" ApplicationName="Firefox" />
  <Association Identifier=".bmp" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Visualizador de fotos de Windows" />
  <Association Identifier=".cr2" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Visualizador de fotos de Windows" />
  <Association Identifier=".gif" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Visualizador de fotos de Windows" />
  <Association Identifier=".ico" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Visualizador de fotos de Windows" />
  <Association Identifier=".jfif" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Visualizador de fotos de Windows" />
  <Association Identifier=".jpeg" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Visualizador de fotos de Windows" />
  <Association Identifier=".jpg" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Visualizador de fotos de Windows" />
  <Association Identifier=".png" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Visualizador de fotos de Windows" />
  <Association Identifier=".tif" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Visualizador de fotos de Windows" />
  <Association Identifier=".tiff" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Visualizador de fotos de Windows" />
  <Association Identifier=".wdp" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Visualizador de fotos de Windows" />
</DefaultAssociations>

And this is with the windows preinstalled:

<?xml version="1.0" encoding="UTF-8"?>
<DefaultAssociations>
  <Association Identifier=".htm" ProgId="FirefoxHTML-E7CF176E110C211B" ApplicationName="Firefox" />
  <Association Identifier=".html" ProgId="FirefoxHTML-E7CF176E110C211B" ApplicationName="Firefox" />
  <Association Identifier=".mht" ProgId="MSEdgeHTM" ApplicationName="Microsoft Edge" />
  <Association Identifier=".mhtml" ProgId="MSEdgeHTM" ApplicationName="Microsoft Edge" />
  <Association Identifier=".svg" ProgId="MSEdgeHTM" ApplicationName="Microsoft Edge" />
  <Association Identifier=".url" ProgId="IE.AssocFile.URL" ApplicationName="Internet Browser" />
  <Association Identifier=".website" ProgId="IE.AssocFile.WEBSITE" ApplicationName="Internet Explorer" />
  <Association Identifier="http" ProgId="FirefoxURL-E7CF176E110C211B" ApplicationName="Firefox" />
  <Association Identifier="https" ProgId="FirefoxURL-E7CF176E110C211B" ApplicationName="Firefox" />
  <Association Identifier="microsoft-edge" ProgId="MSEdgeHTM" ApplicationName="Microsoft Edge" />
  <Association Identifier="microsoft-edge-holographic" ProgId="MSEdgeHTM" ApplicationName="Microsoft Edge" />
  <Association Identifier="ms-xbl-3d8b930f" ProgId="MSEdgeHTM" ApplicationName="Microsoft Edge" />
  <Association Identifier="read" ProgId="MSEdgeHTM" ApplicationName="Microsoft Edge" />
</DefaultAssociations>

I have tried all kind of things editing the file but have no luck.
Any idea?

Many thanks!

Answer 1

Hello @Víctor Martínez

The value is based on where Firefox is installed. 308046B0AF4A39CB corresponds to C:\Program Files\Mozilla Firefox. If your Firefox installation is in C:\Program Files (x86)\Mozilla Firefox, you should use E7CF176E110C211B. For any other install location, you can go to about:support and look at the value for Update Folder. The value is after C:\ProgramData\Mozilla\updates.

In this case, it will be required that you open a query in Mozilla forums, as how to implement those settings, as the mechanisms of association and naming conventions particulars are outside Microsoft's domain.

Hope this helps with your query,

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