Secure Socket Layer, or SSL, protects private data by encrypting it during transmission. To enable SSL encryption, websites use an SSL certificate issued by a certificate authority. When you enter an "https://" address to browse a site, Firefox checks the SSL certificate data to determine whether it is valid. When Firefox encounters an expired or invalid SSL certificate, it blocks the page or displays a warning. However, you might want to disable the warnings or blocking of unencrypted sites for site testing or other reasons. A change to advanced Firefox preferences allows you to prevent the warnings
Step 1
Launch Firefox.
Step 2
Type "about:config" in the address bar and press the "Enter" key. When prompted with the "This might void your warranty!" warning message about changing advanced settings, click the "I'll be careful, I promise!" button.
Step 3
Type "browser.ssl_override_behavior" in the "Filter" box. Double-click the "browser.ssl_override_behavior" value in the "Preference Name" list.
Step 4
Change the value in the "Enter integer value" dialog box from "2" to "1" and click the "OK" button.
Step 5
Close the browser and restart it. Firefox no longer blocks access to sites or displays warnings because of invalid SSL certificates.
