Hi kloris1, do you mean the Outlook website or the Outlook application?

Outlook Website

Will the links open if you use one of the right-click context menu options?

• right-click > Open Link in New Tab
• right-click > Open Link in New Window
• right-click > Open Link in New Private Window

If those do not appear on the menu when you right-click the link, apparently Firefox doesn't see it as a link. Does Outlook display any message about blocking the links for your security?

Outlook Application

Do you get --

• new Firefox tab, stays blank, link doesn't load
• new separate Firefox window, stays blank, link doesn't load
• nothing happens

Does it make any difference whether Firefox was already running at the time you clicked the link?

None of the right click options you presented are displayed in Outlook

Outlook is not blocking anything. If I switch my Win default and don't change anything in Outlook, Chrome comes up fine

As for what I get, it's nothing, nothing happens when I click in an email.

Hi kloris1, I gather from your comments that the answer to my first question is "Outlook application."

Is this a new issue after a recent update, or has your Outlook application never been able to open links in any version of Firefox?

When Firefox is the default browser, do other links and shortcuts on your system open in Firefox, the problem is limited to Outlook? For example, you could test with

• Acrobat or Adobe Reader
• Desktop shortcut to a website
• Another Office application (sometimes all Office applications share a problem, sometimes not)

Yes this is a new issue. It stopped working a few days ago. And it works fine now if the default browser is Chrome.

Other links do not open, for example, in a PDF doc when using a Reader.

This is clearly a FF issue, do you have any suggestions to help with it?

Hi kloris1, when Firefox is the default browser, Windows is supposed to use a particular command line Firefox added to the Windows Registry to start it up with that URL. Possibly that command line is corrupted. Another possibility is that Firefox is getting the command line but can't start up far enough to show a window for some reason. Sometimes this is due to security software killing or stalling Firefox; in other cases the installation might be corrupted.

If you completely exit out of Firefox and try to start it from scratch using a link or shortcut instead of a program shortcut, does anything happen?

Could you check the Windows Task Manager (Ctrl+Shift+Esc), Details tab, to see whether any firefox.exe processes are running?

The attached shows the running FF processes Jscher2000

Hi kloris1, thank you for the screenshot. Sorry, I meant to link those last two paragraphs. First exit Firefox so that the processes disappear, and then test starting it up with just a link to see whether it appears at all, or stalls, or what happens.

See also:

• https://support.mozilla.org/en-US/kb/windows-administrator-launcher-process-error-fix