向Models.py添加DateField时，出现“函数缺少必需的参数'month'（pos 2）”的错误

我是Django的初学者，我正在尝试制作传记应用程序，我在学习Django的官方文档。因此，当我在docs中显示的在models.py中创建DateField时，在运行服务器时出现错误，提示“函数缺少必需的参数'month'（位置2）” 我该怎么办？请帮忙

#models.py
from django.db import models
from django.utils import timezone
import datetime
# Create your models here.

TYPE = (
    ('politician','POLITICIAN'),
    ('poet','POET'),
    ('author','AUTHOR'),
    ('actor','ACTOR'),
    )


class About(models.Model):
    title = models.CharField(max_length = 200, default='')
    context = models.CharField(max_length = 200, default='')
    born_on = models.DateField('Born on')
    died_on = models.DateField( 'Died on')
    main = models.TextField(default='')
    category = models.CharField(choices = TYPE , default = 'poet', max_length = 10)
    image = models.ImageField(blank=True, default='', upload_to='static')
    updated_on = models.DateTimeField(auto_now = True)
    created_on = models.DateTimeField(auto_now_add = True)

    def __str__(self):
        return self.title

    def was_published_recently(self):
        return self.created_on >= timezone.now() - datetime.timedelta(days=1)