I rebooted and when I opened Firefox it was able to reclaim it's defaults. Links are working again.

Try: KB: How to stop displaying "How do you want to open this website?" dialog? - All Free Tools - Free Tool Forums - IDERA Community:

• http://community.idera.com/free-tool-forums/f/352/t/23359

See also:

• https://blog.mozilla.org/futurereleases/2015/07/29/firefox-for-windows-10-how-to-restore-or-choose-firefox-as-your-default-browser/

When I woke up this morning MS Edge had stolen back defaults. I wonder if this is going to be a daily thing.

None of the posts above are valid anymore. I have made a practice of copying links from edge and pasting them into Firefox. As of today, 24/01/2017, that no longer works. I am asked every time what to open it with, and Firefox is not listed. This is a disgusting practice by Microsoft, as Firefox has all my settings within it. We need to make a big noise about this. I can see that if you use cortana, then Microsoft has some rights to use its browser to open links. When my club mag comes in an email, I can no longer open it in anything but edge, which is the worst browser I ever came across, second only to Internet explorer. The whole world should rise up and inundate Microsft with complaints. If we don't, then it surely means the end of Firefox and any other browser in windows 10.

Open Windows Internet Explorer. Have it declared as the default browser, But turn off the option to check this when the browser opens (If you want).

Now do the same thing using Firefox.

FredMcD said

Open Windows Internet Explorer. Have it declared as the default browser, But turn off the option to check this when the browser opens (If you want). Now do the same thing using Firefox.

THanks Fred. That works for the moment. I will check after the next update and see if it still does so.

If it happens again, you can also ask your question here; https://support.microsoft.com http://answers.microsoft.com/en-US/windows/forum/windows_10