You have 14 unapplied migration(s). Your project may not work properly until you apply the migration

You have 14 unapplied migration(s). Your project may not work properly until you apply the migrations for app(s): admin, auth, contenttypes, sessions.
Run ‘python manage.py migrate’ to apply them.

创建django运行的时候报错。
报错原因：
说是有 内容类型和session没有迁移，同时也给出了解决办法。
解决办法：输入这个python manage.py runserver
参考来源书籍：