Firefox won’t let you click “add to exception” option. Why? REDDIT post
Here is how I tested on my Mac Firefox v68,
Disclaimer: USE as your own RISK, you know what you are doing. May HARM your computer or system.
Step to disable HSTS
// Goto about:config 1. search `network.stricttransportsecurity.preloadlist` 2. Set its value from True to FALSE Done ~~
Then I can let the site I wanna visit add to exception list.
Thanks for this post: https://security.stackexchange.com/questions/102279/can-hsts-be-disabled-in-firefox