Debian 8: Firefox say: "no secure connection, please report"
Debian 7: Works fine: "you have to add an exclusion"

Could you say me which file I have to edit?

I use Debian.

Linux Mint 17.2 Ralaela;

Open Software-Sources -> Legitimation-Keys -> Download a Key -> Put your Error Code "BDC3FBAA53029759" in and click on download!

Finish!

For Linux Mint users the other fixes don't work! :/