Python 错误Django cms返回类型错误：issubclass（）arg 1必须是类

我想从Python和DjangoCMS开始，我遵循本教程，但是当我执行

python manage.py cms check

返回

Traceback (most recent call last):
  File "manage.py", line 21, in <module>
    main()
  File "manage.py", line 17, in main
    execute_from_command_line(sys.argv)
  File "C:\Users\Jonatan\PycharmProjects\asesores2\venv\lib\site-packages\django\core\management\__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "C:\Users\Jonatan\PycharmProjects\asesores2\venv\lib\site-packages\django\core\management\__init__.py", line 357, in execute
    django.setup()
  File "C:\Users\Jonatan\PycharmProjects\asesores2\venv\lib\site-packages\django\__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "C:\Users\Jonatan\PycharmProjects\asesores2\venv\lib\site-packages\django\apps\registry.py", line 91, in populate
    app_config = AppConfig.create(entry)
  File "C:\Users\Jonatan\PycharmProjects\asesores2\venv\lib\site-packages\django\apps\config.py", line 142, in create
    if not issubclass(cls, AppConfig):
TypeError: issubclass() arg 1 must be a class

---

使用链接上的方法也让我犯了这个错误

尝试使用djangocms安装程序。说明如下

---

使用该链接上的方法也会导致该错误

尝试使用djangocms安装程序。说明如下

Package               Version
--------------------- -------
Django                2.2.6
django-classy-tags    0.9.0
django-cms            3.7.0
django-formtools      2.1
django-sekizai        1.0.0
django-treebeard      4.3
djangocms-admin-style 1.4.0
mysqlclient           1.4.4
pip                   19.0.3
pytz                  2019.3
setuptools            40.8.0
sqlparse              0.3.0