i was using facebook until about 4 weeks ago. somehow it changed languages and while i was trying to put it back to english i was locked out. this is part of the message i get Firefox detected a potential security threat and did not continue to www.facebook.com because this website requires a secure connection. www.facebook.com has a security policy called HTTP Strict Transport Security (HSTS), which means that Firefox can only connect to it securely. You can’t add an exception to visit this site. The issue is most likely with the website, and there is nothing you can do to resolve it.