It is impossible to add a non nullable field without specifying a default. Django error

I got this following error while trying to add a non-nullable field (description) to an existing model (Category) without specifying a default value.

it is impossible to add a non-nullable field 'description'  to category without specifying a default. This is because the database need something to populate existing rows. 

Please select a fix: 

1) Provide a one-off default now (will be set on all existing rows with a null value for this column) 

2) Quit and manually define a default value in models.py 

select an option:

description=models.TextField(max_length=500,blank=False)

description=models.TextField(max_length=500,blank=False,null=True)

You need to run python manage.py makemigrations followed by python manage.py migrate to apply the changes to your database.

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