How to handle insecure connection on firefox

While using firefox on ubuntu, few of the websites showed up with
Insecure Connection :

The issue can be resolved in few steps mentioned below:

  1. Open Firefox
  2. Type - about:config in the adrress bar
  3. Select - I will be careful, I promise
  4. Write http2 in the search bar
  5. Double click network.http.spdy.enabled.http2 to make its boolean value false.
    That’s it!!
    Reopen the website, it will work.