To reproduce bug:1. open app, 2. click on fullscreen button3. rotate device twice4. click back twice (exit app)5. look at logcat

FragmentsBug.java

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new FrameLayout(this) {{
            setId(42);
        }});
        
        if (savedInstanceState == null) {
            getSupportFragmentManager()
                    .beginTransaction()
                    .replace(42, new Master())
                    .commit();
        }
    }


    public static class Master extends Fragment {
        Holder h;

        @Override
        public void onCreate(@Nullable final Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            if (savedInstanceState == null) {
                Log.d("TAG", "create");
                getChildFragmentManager()
                        .beginTransaction()
                        .add(h = new Holder(), "holder")
                        .commit();
            } else {
                h = (Holder) getChildFragmentManager().findFragmentByTag("holder");
            }
        }

        @Nullable
        @Override
        public View onCreateView(final LayoutInflater inflater, @Nullable final ViewGroup container, @Nullable final Bundle savedInstanceState) {
            return new Button(container.getContext()) {{
                setText("NEXT");
            }};
        }

        @Override
        public void onViewCreated(final View view, @Nullable final Bundle savedInstanceState) {
            h.listener = integer -> ((Button) view).setText("" + integer);
            view.setOnClickListener(v ->
                    getFragmentManager()
                            .beginTransaction()
                            .replace(42, new Master())
                            .addToBackStack(null)
                            .commit());
        }

        @Override
        public void onDestroyView() {
            super.onDestroyView();
            h.listener = null;
        }
    }

    public static class Holder extends Fragment {
        interface Listener {
            void call(int i);
        }

        private int i;
        private final Handler handler = new Handler();

        public Holder() {
            Log.d("TAG", "constuctor");
            setRetainInstance(true);
        }

        Listener listener;

        @Override
        public void onCreate(@Nullable final Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            if (savedInstanceState != null) {
                i = savedInstanceState.getInt("me");
            }
            notifyListeners(i);
        }

        @Override
        public void onSaveInstanceState(final Bundle outState) {
            super.onSaveInstanceState(outState);
            Log.d("TAG", "save" + this);
            outState.putInt("me", i);
        }

        @Override
        public void onDestroy() {
            handler.removeCallbacksAndMessages(null);
            Log.d("TAG", "dest" + this);
            super.onDestroy();
        }

        private void notifyListeners(final int i) {
            this.i = i;
            Log.d("TAG", "" + this + " counter " + i + "");
            if (listener != null) {
                listener.call(i);
            }
            handler.postDelayed(() -> notifyListeners(i + 1), 1000);
        }

        
    }
}