What site or screenshot error? Did you try to restart the computer as well as sometimes a restart reconnects to give access back.

Yeah, I restarted but the problem persists. I just checked and found that a new version of Firefox was installed yesterday. The new version is obviously the problem, so I'll try to rollback to a previous version.

It reminds me of the following thread (unsolved?) where you can find some additional suggestions:

https://support.mozilla.org/questions/1418021

It reminds me of the following thread (unsolved?) where you can find some additional suggestions: https://support.mozilla.org/questions/1418021

Does this mean that Mozilla will not be fixing the problem?

It depends on what the problem is. I've seen two user reports so far that their Firefox has zero ability to connect to sites and not enough clues to identify the root cause.

Did you try the "Clean Reinstall" test?

If that seems too drastic, you could try this first:

New Profile Test

This takes about 3 minutes, plus the time to test some problem site(s).

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

Take a quick glance at the page and make a mental note of which Profile has this notation: This is the profile in use and it cannot be deleted. That is your current default profile.

Click the "Create a New Profile" button, then click Next. Assign a name like Test2023, ignore the option to relocate the profile folder, and click the Finish button.

Firefox will switch your default profile to the new one, so click the Set as Default Profile button for your regular one to avoid an unwanted surprise at your next startup.

Scroll down to Test2023 and click its Launch profile in new browser button.

Firefox should open a new window that looks like a brand new, uncustomized installation. (Your existing Firefox window(s) should not be affected.) Please ignore any tabs enticing you to connect to a Sync account or to activate extensions found on your system to get a clean test.

Can Firefox make any connections in the new profile?

When you are done with the experiment, you can close the extra window without affecting your regular Firefox profile. (Test2023 will remain available for future testing.)

Update: I contacted Kaspersky and they had me uninstall/reinstall my virus protection which seems to have been the problem. From what I've gathered, it looks like this has been a problem (on their end) for years. Thanks for your help, though!

Hello,

I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution.

Thank you for contacting Mozilla Support.