完整报错内容：

django.core.exceptions.ImproperlyConfigured: Requested setting INSTALLED_APPS, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.

解决办法：

找到Pycharm软件右上角（如下图），选择带有dj样式的项目，点击运行就解决了。