SSL error in mozilla browser
There can be multiple reason for it but please check these two and see if it works for you:
1) There can be a possibility that the site you are trying to access is not a secured website but you are trying to access it with secure channel for example http://www.toolsqa.com. If you try to access it as https://www.toolsqa.com you would get the same error.
2) Also check the connection settings of your firefox browser:
Tools > Options > Advanced : Network : Connection > Settings
Select “No Proxy” for now and give it a try.