I have two fragments. Fragment A implements a listener. when I want to open fragment B, I set this listener directly in it and hold it as a lateinit var. Here is my problem. when i rotate screen in fragment B, I get error that I havent initialize the lateinit variable. How can i solve this?

Have you looked at the Fragment Result API? https://developer.android.com/training/basics/fragments/pass-data-between

Thanks, I hope it will work.