See https://www.facebook.com/theoldlayout/posts/167793385055475

See https://www.facebook.com/theoldlayout/posts/167793385055475

See https://www.facebook.com/theoldlayout/posts/167793385055475

It may not work for you, but it's still working for others (like me). I explain this in detail in my post: https://www.facebook.com/theoldlayout/posts/167793385055475 and also in the message that appears when the extension tries to switch.