What's your computer system and Firefox version?

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}

Thanks Fred,

I am running Windows 10 & have uninstalled Firefox, removed files from Program Files, App Data, Registry & used CClenaer to cleanup any remains. Reinstalled latest version of Firefox with no go. Reinstalled latest Firefox Setup 57.0b3 version to test with no avail. Created a new user profile to test but the same error on the new profile too. I have tested my Antivirus software & local system firewall & see no issues here. ANy other suggestions?

Thanks in Advance

Could you try doing a full uninstall again and delete Windows Temp Files as well. I would also suggest going through the registry and deleting all Firefox/Mozilla entries or use a registry cleaner after you have uninstalled and rebooted.

Try reinstalling with the full installer from here : https://www.mozilla.org/en-US/firefox/all/ (as you do not say if have tried the full or just installed with the Stub)

Please let us know if this solved your issue or if need further assistance.

Hi, I tried the same & still same issue. I am not sure what's blocking it