运行总是提示： Are you sure it's installed and available on your PYTHONPATH environment variable? Did you forget to activate a virtual environment?

怎么解决的？我的Python环境变量也添加了啊，可还是报上面的错误。

报错信息如下：

D:\DjangoProject\django_introduction>python manage.py runserver

Traceback (most recent call last):

  File "manage.py", line 8, in <module>

    from django.core.management import execute_from_command_line

ModuleNotFoundError: No module named 'django'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):

  File "manage.py", line 14, in <module>

    ) from exc

ImportError: Couldn't import Django. Are you sure it's installed and available on your PYTHONPATH environment variable? Did you forget to activate a virtual environment?