The full error is: “Unknown method ‘executePendingTransactions’ of 'android.support.v4.app.FragmentTransaction”.
I’ve imported the following packages (I’ve imported more, but these are the most relevant, I think):
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.app.FragmentManager;
import android.support.v7.app.AppCompatActivity;
Must I update a think? How can I solve this problem?