因為不能刪掉migrations文件夾。
更改default字段

from future import unicode_literals
from django.db import models, migrations
import datetime

class Migration(migrations.Migration):
dependencies = [ ('App11', '0003_remove_choice_question'), ]
operations = [
migrations.AddField(
model_name='choice',
name='question',
field=models.ForeignKey(default=1, to='App11.Question'), preserve_default=False, ),
]

解決的話刪掉migrations 文件夾重新生成即可