I'm using these instructions for making the FireFox browser the default browser via GPO: https://support.mozilla.org/en-US/kb/make-firefox-enterprise-default-browser#firefox-enterprise:win10: and I'm unable to do so successfully. When I perform the steps what happens is that no browser becomes the default. Trying to open an html document causes Windows 10 to ask the user to pick which browser they would like to be the default web browser. I can choose Firefox at that point but if I reboot or do a gpupdate /force, the default app for browser goes back to not having one selected. I can use the same steps to a file at the same network location to make Google Chrome the default browser without issue, but when I switch back to trying to make Firefox the default the same problem returns. I've tried the rapid release version and the ESR version. I have also uninstalled and reinstalled Firefox. I feel like the issue is related to the default associations xml file from the instructions which states ProgId="FirefoxHTML . If you look in the windows registry, "FirefoxHTML" is not listed as an option for either of these keys: Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.html\OpenWithProgIds Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.htm\OpenWithProgIds If you go here: Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Clients\StartMenuInternet\Firefox-308046B0AF4A39CB\Capabilities\URLAssociations Instead of "FirefoxHTML" it lists "FirefoxURL-308046B0AF4A39CB" for the http and https url associations. Does anyone have a solution to this problem or another way to make Firefox the default browser for multiple machines remotely?