As of Firefox 59 it looks like self signed certificates no longer work. "The certificate is not trusted because it is self-signed. " I use self signed certificates when developing sites locally, and I've had to jump through hoops in order to get this to work in the past. The documentation specified via "Learn More" link is outdated as there no longer is a mechanism to add exceptions. It seems like every browser handles this differently as Chrome accepts trusted certs within "Keychain Access" but Firefox does not. Is there updated documentation on how to allow self signed certs for the newest version of Firefox?