Firefox keeps popin this shit for some sites that isn't supposed to (like 4chan homepage, kissanime ect...)
I add exception but that doesn't do anything
Well OP's problem was solved but this is pretty relevant to this thread so I'm going to post it anyway.
SHA1 is being disabled for new certificates due to the weakness in the algorithm. If you have a site that uses SHA1 already it will be allowed to continue but if the cert is issued after a certain date firefox will throw up a warning similar to the one in OP's post.