使用Django CMS定制用户模型.无法解析cms.PageUser的基础

users.models：

from django.db import models
from django.contrib.auth.models import AbstractUser


class User(AbstractUser):
    bio = models.TextField(max_length=500,blank=True)
    location = models.CharField(max_length=30,blank=True)
    birth_date = models.DateField(null=True,blank=True)

这里的项目设置：

设置：

INSTALLED_APPS = [
    'djangocms_admin_style','django.contrib.auth','django.contrib.contenttypes','django.contrib.sessions','django.contrib.admin','django.contrib.sites','django.contrib.sitemaps','django.contrib.staticfiles','django.contrib.messages','users','cms','menus',...
]

AUTH_USER_MODEL = 'users.User'

为什么我有这个错误？

manage.py makemigrations用户

django.db.migrations.state.InvalidBasesError: Cannot resolve bases for [<ModelState: 'cms.PageUser'>]
This can happen if you are inheriting models from an app with migrations (e.g. contrib.auth)
 in an app with no migrations; see https://docs.djangoproject.com/en/1.8/topics/migrations/#dependencies for more