Sometime we want to browse to internet site without correct security settings and the option of “accept the risk and continue” is missing .The reason is HSTS which stands for “HTTP Strict Transport Security” . This setting is blocking the option to continue to the web site although security issue.
To clear the site from HSTS you need to :
1. navigate to about:support (type this in an empty TAB) 2. Scroll down to Profile Folder setting line -> Click Open Folder 3. Find The file name SiteSecurityServiceState.txt This file contain all the cached HSTS and HPKP (Key Pinning, a separate HTTPS mechanism) settings for domains you have visited 4. Search for the domain you want to clear the HSTS settings for and delete it from the file