python - Django 抽象模型迁移与南给出错误

Question

我有以下模型：

class MemberCategory(BaseModel):

    """
    Contains Predfined Category Types
    """
    title = models.CharField(null=True, blank=True, max_length=100)
    description = models.TextField(null=True, blank=True)
    slug = models.SlugField(null=True, blank=True)

基本模型如下所示：

class BaseModel(models.Model):

    """
    An abstract base class model that provides self-managed "created" and
    "modified" multi tenant fields.
    """
    creation_date = models.DateTimeField(auto_now_add=True)
    modification_date = models.DateTimeField(auto_now=True)

    class Meta:
        abstract = True

现在我去org在我的 MemberCategory 中添加一个字段，以便新模型如下所示：

class MemberCategory(BaseModel):

    """
    Contains Predfined Category Types
    """
    title = models.CharField(null=True, blank=True, max_length=100)
    description = models.TextField(null=True, blank=True)
    slug = models.SlugField(null=True, blank=True)
    orgs = models.ForeignKey(Org, null=True, blank=True)

在此之后我做 -python manage.py schemamigration <app_name> --auto没有错误，一切都很好。

然后我这样做python manage.py migrate <app_name>会引发以下错误 -

KeyError: u'creation_date'

我收到此错误的任何原因？