Links I click on will not open

How does that exhibit? Something spins… waits… hangs… shows errors? If you don't click or open links, did you use any other browser to submit this question? Or it affects just some specific sites?

If I click on a link in an e-mail, I get a small window like this: (Okay,it will not let me attach my screenshot) The little window says "Email" and something else and "Open with Firefox." If I click on that, it all just disappears. Nothing happens.

If I click on a link someone sent me in a text,, or somewhere else (not e-mail), nothing happens.

This sounds like something on your macOS — before the browser even gets involved. Not sure if anyone here will be able to help without an image of what's happening, it might eventually be a question for Apple support.

However if you otherwise have no issues navigating, you can always right–click (or Control + click) on these links, select "Copy", and then in Firefox "Paste" that link in address bar and navigate there manually this way as a workaround for time being.

I've been screen-sharing with Apple Care for 2 days now! No one has a clue what to do. They just sent me to Firefox for answers.

Yes, I can do all those things. But we click on things hundreds of times a day. (I do, for work, especially.) This quintuples the number of clicking steps involved. I would get 1/5 of the work done. That's not an option. I need to figure this out. What did Firefox just do (I've seen all the announcements) that might have affected links??

Probably nothing. There's an issue on Tahoe that changed some SDKs, and the first external link opened at cold start is dropped during launch and needs to be clicked twice. Users with profile selector hit the issue analogously on Tahoe, and need to click again. Once the browser is running no reports of anything. And no windows or dialogs as mentioned in the first post.

If you feel this was related to an update, can you post from which version you updated, and on which version this behavior started? (Your update history is under Help › More Troubleshooting Info › Show Update History.)

This question has no troubleshooter data attached, so it's not even obvious what version of macOS you're running. Do the external links fail mainly from Apple software, like iMessage and Apple Mail?