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}

Although I updated the Zone Alarm security software, removed firefox.exe 51.0.1, crashreporter.exe 54.0.1, and pingsender.exe 54.0.1 from its Application Control list and added these executables back to the list (and their new version numbers were all listed as 71.0), I still get the "Unable to connect Firefox can’t establish a connection to the server at ….". I'll try logging out and a cold boot.

Logging out and a cold boot (after removing and adding to the Application Control list of my internet security software) did not resolve the issue.

Windows 10's "Firewall and network protection" window refers me to "ZoneAlarm Extreme Security Firewall" where I previously removed and added three Firefox executables without success. Because Opera and

Disable ZoneAlarm. Anything?

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

FredMcD,

When I disabled Zone Alarm's firewall in the Pu account neither Opera nor Firefox could reach secure websites.

When I did a safe mode with networking reboot both Firefox and Opera loaded webpages from secure websites from Pu. When I then did a regular reboot those browsers again could not connect. How can I apply these results?

Thank you

You'll have to find out what is causing the problem through trial and error. The program likely to cause this issue is either firewall or virus protection. Malware is also a possibility but I don't believe that is the issue here.

SOLVED BY REPLACING MY SECURITY SOFTWARE I uninstalled Zone Alarm Extreme Security version 15.0.159.17147 and replaced it with version 15.8.026.18228. This product does have its own firewall.

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.

I have been fighting this issue for months. It appear to be related something within the program not waking up after sleep. On a reboot it works fine, till a sleep. The program appears normal but it just will not connect to any site after sleep (this is my best guess as to where this happens). Edge and Chrome work fine but all my bookmarks are in Firefox, (it's been my fav sense it came out). I hate Edge, might have to go with Chrome. The only way I can get it to re connect is to reboot. Been doing that several time a day. I have tried every one of the guidelines here and on the net including all the virus and malware software recommendations. Contacted both McAfee and Malware Bytes and after remote logins it is not them. It is a Firefox software issue. I have uninstalled and re installed it three time and the issue remains. I should not have to jump through all these hoops with security as every other program I have works fine, And I have tones of high end cad programs. Does this ring a bell with anyone?

Thanks

mjfator
Many have reported issues about Firefox and sleep.

Please go to the top of any support.mozilla.org web page and use the Get Community Support link: https://support.mozilla.org/en-US/questions/new

Select the product for what the problem is (Firefox or whatever). Now select the category for the problem. At the bottom is Other.

Describe the problem in brief (one line). Then press <enter>. The website will display any prior posts that might help you. If nothing on the list can help, at the bottom press the button; None Of These Solve My Problem.

Now enter all the relative information on the problem. At the bottom of this, you can Add Images.

Under this is Troubleshooting Information. Please press the Share Data button. This will let us look at your system details. No Personal Information Is Collected.