python flask. ошибка запуска сервера

версия python: 3.8.5

сделал виртуальное окружение через venv, запустил venv/Scripts/activate.bat, установил flask. создал файл app.py в корне проекта(projects\blog\app.py)
дерево проекта получилось следующее:

blog\
    venv\
        Include\...
        Lib\...
        Scripts\...
        pyvenv.cfg
    app.py

в файле app.py определил следующий код:

from flask import Flask

app = Flask(__name__)

@app.route('/')
    def index():
    return "main page"

if __name__ == "__main__":
    app.run(debug=True)

при запуске команды python app.py появляется следующая ошибка:

(venv) C:\Users\usr\Desktop\projects\blog>python app.py
* Serving Flask app "app" (lazy loading)
* Environment: production
  WARNING: This is a development server. Do not use it in a production deployment.
  Use a production WSGI server instead.
* Debug mode: on
* Restarting with stat
* Debugger is active!
* Debugger PIN: 130-916-178
Exception in thread Thread-1:
Traceback (most recent call last): File "C:\Users\usr\AppData\Local\Programs\Python\Python38-32\lib\threading.py", line 932, in _bootstrap_inner
self.run()
File "C:\Users\usr\AppData\Local\Programs\Python\Python38-32\lib\threading.py", line 870, in run
self._target(*self._args, **self._kwargs)
File "C:\Users\usr\Desktop\projects\blog\venv\lib\site-packages\werkzeug\serving.py", line 996, in inner
srv = make_server(
File "C:\Users\usr\Desktop\projects\blog\venv\lib\site-packages\werkzeug\serving.py", line 847, in make_server
return ThreadedWSGIServer(
File "C:\Users\usr\Desktop\projects\blog\venv\lib\site-packages\werkzeug\serving.py", line 740, in __init__
HTTPServer.__init__(self, server_address, handler)
File "C:\Users\usr\AppData\Local\Programs\Python\Python38-32\lib\socketserver.py", line 452, in __init__
self.server_bind()
File "C:\Users\usr\AppData\Local\Programs\Python\Python38-32\lib\http\server.py", line 140, in server_bind
self.server_name = socket.getfqdn(host)
File "C:\Users\usr\AppData\Local\Programs\Python\Python38-32\lib\socket.py", line 756, in getfqdn
hostname, aliases, ipaddrs = gethostbyaddr(name)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xcf in position 6: invalid continuation byte

pip freeze:

(venv) C:\Users\usr\Desktop\projects\blog>pip freeze
click==7.1.2
Flask==1.1.2
Flask-SQLAlchemy==2.4.4
itsdangerous==1.1.0
Jinja2==2.11.2
MarkupSafe==1.1.1
SQLAlchemy==1.3.18
Werkzeug==1.0.1