Using Filepicker.io and Django South migrations together. South cannot introspect some fields, if you are redirected to http://south.aeracode.org/wiki/MyFieldsDontWork and looking for a solution specific to Filepicker's FPFileField, this is the code you're looking for.

models.py

from django_filepicker.models import FPFileField

from south.modelsinspector import add_introspection_rules
add_introspection_rules([], ["django_filepicker\.models\.FPFileField"])

class Stuff(models.Model):
    preview = FPFileField(upload_to='previews', null=True, blank=True)