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What does the "browser.shell.checkDefaultBrowser" setting check?

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New Contributor

What does the "browser.shell.checkDefaultBrowser" setting check?

I wish to set Firefox as my default web browser, i.e. Firefox should open the links I click from other programs such as Steam. However, I do some web development work also and any local .html files I have I wish to open in gVim instead of Firefox most of the time.

I'd initially set Firefox as my default browser, and today changed the file association of .html files to be opened in gVim. External links, say from Steam, are still getting opened by Firefox, but Fx now seems to think it's not the default browser and gives that initial dialogue every time I reopen it.

I can obviously disable the check itself, but I would prefer to have it on for external URLs to prevent nasty surprises. So, I would like to know what exactly Firefox checks for when this setting is turned on - it seems apparent that there are two separate settings in Windows for which program opens .html files and which one opens clicked URLs (since I'm able to set two different programs successfully), so does Firefox check both of those settings, or does it just check the association of .html files? Is it possible to change it somehow to check for the association of clicked URLs instead?

3 REPLIES
Site Moderator

Re: What does the "browser.shell.checkDefaultBrowser" setting check?

If not all required registry keys link to Firefox then you will get this alert on each start that Firefox isn't set as the default browser. You will either have to disable that check or leave all settings as they are set by Firefox.

  • Tools > Options > Advanced > General: System Defaults:
    "Always check to see if Firefox is the default browser on startup"
New Contributor

Re: What does the "browser.shell.checkDefaultBrowser" setting check?

@cor-el Thanks for your reply. Can you mention what the "required registry keys" are that Fx checks for? Perhaps then I can disable this check and instead write a script myself to check only the registry keys I need.

Site Moderator

Re: What does the "browser.shell.checkDefaultBrowser" setting check?

You can do a search in the registry editor (Ctrl+F) for firefox to see which keys point to the firefox.exe program.