Firefox Won't Even TRY to Open Website
There are no restrictive settings turned on. I have turned off all known restrictive settings except in config. The website will open in Avast Secure Browser. Firefox will not even TRY to open the website. I can either use a bookmark or type in the address. Firefox simply "blinks" and then clears the address line and displays the previously opened page or a blank page if that was what I started with. ALL history, cookies, and settings have been cleared. Nothing. Avast has been disabled until I restart the computer. Nothing. I've turned off the firewall. No change. Yes, I have an older version. No, I will not update. There is no update for a specific add-on.
Opaite Mbohovái (1)
Could you try:
New Profile Test
This takes about 3 minutes, plus the time to test some site(s).
Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.
Click the Create a New Profile button, then click Next. Assign a name like Dec2018, ignore the option to relocate the profile folder, and click the Finish button.
After creating the profile, scroll down to it and click the Set as default profile button below that profile, then scroll back up and click the Restart normally button. (There are some other buttons, but please ignore them.)
Firefox should exit and then start up using the new profile, which will just look brand new. Please ignore any tabs enticing you to connect to a Sync account or to activate extensions found on your system so we can get a clean test.
Can you load sites in the new profile?
When you are done with the experiment, open the about:profiles page again, click the Set as default profile button for your normal profile, then click the Restart normally button to get back to it.
ScubaGolfJim- said
No, I will not update. There is no update for a specific add-on.
Do you mean DownThemAll! version 3.0.8? That release was compatible with Firefox 52 ESR, which was updated much more recently than Firefox 47.
It also may work in Seamonkey and Waterfox if you can't live without it.