您的 manage.py 正在引用一个应用程序（ notifications ）。由于Django环境尚未设置，Django会抱怨DJANGO_SETTINGS_MODULE被设置。

Yourmanage.py is referencing an application (notifications). This forces Django to complain about DJANGO_SETTINGS_MODULE being set because the Django environment hasn't been set up yet.

顺便说一下，您可以手动强制环境设置，但是老实说，我会不要在manage.py中执行此操作。这在我看来并不是一个很好的做法。

Incidentally, you can force the enviroment setup manually, but honestly I wouldn't do this in manage.py. That's not really a good practice in my opinion.

以下是您可以从任何应用程序（或程序中）手动设置Django环境：

Here is how you can manually setup the Django environment from within any app (or program for that matter):

# set up the environment using the settings module
from django.core.management import setup_environ
from myapp import settings
setup_environ(settings)