ImportError: cannot import name 'DEFAULT_CHANNEL_LAYER' from 'channels'

运行项目出现错误：
ImportError: cannot import name ‘DEFAULT_CHANNEL_LAYER’ from ‘channels’
我的django配置文件里是这样的

CHANNEL_LAYERS = {
    "default": {
        "BACKEND": "channels_redis.core.RedisChannelLayer",
        "CONFIG": {
            "hosts": [("localhost", 6379)],
        },
    },
}

在manage.py中也有声明

os.environ['DJANGO_SETTINGS_MODULE'] = 'Web.settings'

最后：

pip uninstall asgi_redis
pip uninstall channels-redis
pip uninstall channels # Successfully uninstalled channels-2.1.5
pip install channels 
# Successfully uninstalled daphne-2.2.3
# 安装信息中出现daphne~=2.3
#Found existing installation: daphne 2.2.3
#    Uninstalling daphne-2.2.3:
#      Successfully uninstalled daphne-2.2.3
#Successfully installed channels-2.2.0 daphne-2.3.0

最后执行runserver没有报错了， 也许是channels，daphne版本问题造成的