passenger cpanel deploy flask project 404 not found

The basic problem is that I can run the hello world app but can't make other routes work. I followed a tutorial. Project structure is as below: testapp __init__.py passenger_wsgi.py app(folder) --templates(folder) --static(folder) The codes are: __init__.py: import os from flask import Flask, request, render_template, redirect, url_for project_root = os.path.dirname(os.path.realpath('__file__')) template_path = os.path.join(project_root, 'app/templates') static_path = os.path.join(project_root, 'app/static') app = Flask(__name__, template_folder=template_path, static_folder=static_path) @app.route('/') def index(): return 'Hello, World' passenger_wsgi.py: import os import sys import importlib.util sys.path.insert(0, os.path.dirname(os.path.realpath('__file__'))) spec = importlib.util.spec_from_file_location("wsgi", "__init__.py") wsgi = importlib.util.module_from_spec(spec) spec.loader.exec_module(wsgi) application = wsgi.app I followed the tutorial and everything went well. Then I tried to dig deeper. (1) I tried to add @app.route('/login') def login(): return 'login page.' when I tried to access