With the newest Firefox, some Security Certificates have been disabled because of issues with new mal-ware. Can you check with the site on what Security Certificates they are using? (SSL and TSL encryption protocols) https://developer.mozilla.org/en-US/Firefox/Releases/37/Site_Compatibility#Security https://blog.mozilla.org/security/2014/09/23/phasing-out-certificates-with-sha-1-based-signature-algorithms/ https://blog.mozilla.org/security/2015/01/28/phase-2-phasing-out-certificates-with-1024-bit-rsa-keys/ https://blog.mozilla.org/security/2014/10/14/the-poodle-attack-and-the-end-of-ssl-3-0/ Run your website through https://www.ssllabs.com/ and you can see all security issues that need to be fixed. https://www.ssllabs.com/projects/index.html Qualys SSL Labs Projects https://www.ssllabs.com/ssltest/viewMyClient.html SSL/TLS Capabilities of Your Browser The SSL client test shows the SSL/TLS capabilities of your browser.

I think that you need to access this website via HTTP and not via secure HTTPS, so Firefox forces https:// then you need to make an exception and load the site via http://. I can't get it to work with HTTPS-Only enabled because the server appears to have a valid certificate installed (disabling HTO for this site doesn't work), so I need to disable this feature to be able to open the site via http:// *http://publichealth.lacounty.gov/