What OS? If windows, home or pro? If windows, are you running any security software besides MS Defender? What version of Firefox? Are you getting that on the home page? A full browser screenshot would be helpful. Message seems pretty clear to me. What add-on(s) are you running? Did you try with Firefox in Troubleshoot Mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#w_how-to-start-firefox-in-4troubleshoot-modesf5safe-modesf I get no messages and my blockers are on. see screenshot