Bug: ProgID is incorrect, it should be "FireFoxHTML" instead of  "FirefoxURL-308046B0AF4A39CB".  This causes the instructions to make FireFox the default web browser via GPO on Windows 10 clients to fail
Status: RESOLVED
Priority: --
Resolution: FIXED
Created: 2021-05-04 18:35:10+00:00
Resolved: 2021-05-07 15:02:00+00:00

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:88.0) Gecko/20100101 Firefox/88.0

Steps to reproduce:

I used these instructions for making Firefox the default web browser on Windows 10/2012 clients/servers: https://support.mozilla.org/en-US/kb/make-firefox-enterprise-default-browser#firefox-enterprise:win10:

Download the enterprise version of Firefox (either rapid release or ESR) and install on a Windows 10 or Windows 2012 client.  These instructions call for applying a GPO on Windows machines that calls a separate Default Associations xml document that looks like this:

<DefaultAssociations>

 <Association Identifier=".htm" ProgId="FirefoxHTML" ApplicationName="Firefox" />
 <Association Identifier=".html" ProgId="FirefoxHTML" ApplicationName="Firefox" />
 <Association Identifier="http" ProgId="FirefoxHTML" ApplicationName="Firefox" />
 <Association Identifier="https" ProgId="FirefoxHTML" ApplicationName="Firefox" />

</DefaultAssociations>

Put this file in a location that is accessible to the client and have the GPO point to that file (per the instructions linked above).  These same steps work just fine with Google Chrome using the exact same file at the same location if you just change the progid and application name to match what Google uses (ProgId="ChromeHTML" ApplicationName="Google Chrome") 


Actual results:

When you follow these steps for Firefox, and apply the GPO on the windows 10 client (applying the GPO with the command "gpupdate /force and logging out of Windows and back in) there will be no browser set as the default browser.  Opening an HTML document or clicking on an http/https link will bring up the Windows prompt to select the application you would like to be the default browser.

If you manually make Firefox the default browser and logout and log back into Windows the problem returns since as expected the GPO applies again at login.  This problem does not occur if you perform the same steps but with/for Google Chrome.

I believe the issue is related to the ProgID portion of the default associations xml document listed in the instructions.  If you manually set Firefox as the default web browser in Windows 10 or Windows 2012 and then go to:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\Shell\Associations\URLAssociations\(http|https)\UserChoice
it shows that the progid of Firefox is "FirefoxURL-308046B0AF4A39CB"

If you edit the default associations xml document from the instructions above and change the http and https sections so that the progid is "FirefoxURL-308046B0AF4A39CB" the problem does not occur and everything works as expected.  If this progID changes periodically with updates then this will break GPO's that use this ProgID to make Firefox the default web browser.

I reproduced this issue on multiple machines on new installs as well as machines where Firefox was already installed and just updated to the latest release.


Expected results:

The expected result is that the GPO, along with the default associations file should make Firefox the default application in Windows 10 clients whenever a user logs into windows (just as the instructions state).  Unfortunately this is broken.