django启动服务时报错：RuntimeError: Model class index.models.User doesn't declare an explicit app_label and isn't in an application in INSTALLED_APPS.

在django框架中用命令启动服务时报如下错误：

　　RuntimeError: Model class index.models.User doesn't declare an explicit app_label and isn't in an application in INSTALLED_APPS.

解决方法：

　　我是这样解决的：

　　检查setting.py里面的INSTALLED_APPS，发现应用没有注册。把应用注册之后，重启服务就好了

　　其它解决方法，以后遇到了再补充。