Fragment must be a public static class to be properly recreated from instance state

The error is not especially weird. If you were not getting this error before, that was weird.

Android destroys and recreates fragments as part of a configuration change (e.g., screen rotation) and as part of rebuilding a task if needed (e.g., user switches to another app, your app's process is terminated while it is in the background, then the user tries to return to your app, all within 30 minutes or so). Android has no means of recreating an anonymous subclass of DialogNew.

So, make a regular public Java class (or a public static nested class) that extends DialogNew and has your business logic, replacing the anonymous subclass of DialogNew that you are using presently.

I recreated my fragment from scratch, it's solved the problem for me.

New -> Fragment -> Fragment (Blank) and you uncheck the 2nd box before confirming.

Edit: You probably don't want to do this... See the comments.

The code sample looks similar to what I had suggested over here, and I also recently discovered that the solution I had there was not working anymore. I've updated my answer there for Java7, but if you have Java8 the solution is super easy:

(I haven't tested this yet)

public class DialogNew extends DialogFragment {    private View rootView;    private String title;    private String message;    // Do nothing by default    private Consumer mSuccess = (boolean b) -> {};    private Runnable mCancel = () -> {};    public void setArgs(String title, String message) {        Bundle args = new Bundle();        args.putString("title", title);        args.putString("message", message);        setArguments(args);    }    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setStyle(STYLE_NO_TITLE, 0);    }    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {        rootView = inflater.inflate(R.layout.fragment_new_dialog, container, false);        // use mSuccess.accept(boolean) when needed        init();        setListeners();        return rootView;    }    public void setSuccess(Consumer success) {        mSuccess = success;    }    public void setCancel(Runnable cancel) {        mCancel = cancel;    }}

Then in the Main activity:

public class MainActivity extends BaseActivity {        public void showNewDialog(int type, String title, String message) {            final DialogNew dialog = new DialogNew();            dialog.setArgs(title, message);            dialog.setSuccess((boolean isLandscape) -> {                //....            });            super.showDialogFragment(dialog);        }}