Type about:preferences#advanced<Enter> in the address bar.

Under Advanced, Select Network.

[v56+] Type about:preferences#general<enter> in the address bar. Look for Network. +++++++++++++++++++++ Look for Configure How Firefox Connects and press the Settings button. If you are using a proxy, make sure those settings are correct. If there is no proxy, first try No Proxy. If there is a problem, then try System Proxy.

Some problems occur when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

• Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
• Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet {web link}

Both no proxy and system proxy did not work.

Do you mean the problem you first posted on March 3rd is continuing and has never been resolved?

https://support.mozilla.org/questions/1252039

What message is Firefox giving you when you try to connect to a popular website? Usually you can copy/paste from the error page into a reply here.

If you are getting a secure connection problem, and there's an "Advanced" button, please click that and copy/paste the technical details from that section.

Yes, this is the same problem from months ago. I'm computer literate, by the way. I just don't have the patience to deal with the Firefox browser. I get extremely frustrated with it and set it aside to attend to more pressing issues. It's either that or throw my computer against the wall and cuss like a sailor for a half hour, so I choose to simply walk away and forget about it for a while. Usually a very long while. Screen capture is attached.

Is there a problem with other programs using the web?

Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there?

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

I've tried safe mode before, and the issue was still there. I also completely removed my antivirus, Eset NOD32, from my computer, and the connection problem was still there. I changed the firewall setting to allow Firefox, and the connection problem was still there. I changed Firefox settings to "no proxy" and "system proxy," and the connection problem was still there. My other browsers such as Chrome, SRware Iron, and MS Edge all work fine. The connection problem only occurs with Firefox.

Same error for these?

• Non-secure address: http://www.example.com/
• Fixed IP address: https://1.1.1.1/help

Firefox has an HTTP logging feature. It's quite verbose so I find it very challenging to follow. However, if no connections are working, it might not be too bad. If you want to try creating a log, you can do that using the following internal page:

about:networking#logging

Something in the log might help someone determine the point of failure.

More info: https://developer.mozilla.org/docs/Mozilla/Debugging/HTTP_logging

Just a shot in the dark.

Press the Alt or F10 key to bring up the toolbar. Select File. Look for Work Offline.