loaddata comments troubles

[Andrey Andreev]

Why when i try loaddata django_comments data from json|xml file i recieve error: django.db.models.fields.related_descriptors.RelatedObjectDoesNotExist: Problem installing fixture '/Users/stormy/dev/mezz/_backups/back_generic_django_comments.json': Comment has no content_type.

Mezzanine 4.3.1

Django 1.11.20

Python 2.7.10

1. first i export data:

(env)Mini:mezz stormy$ python manage.py dumpdata generic django_comments --format json --indent 4 > _backups/back_generic_django_comments.json

2. then i try loaddata:

(env)Mini:mezz stormy$ python manage.py loaddata _backups/back_generic_django_comments.json 

Traceback (most recent call last):
  File "manage.py", line 14, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/stormy/dev/mezz/env/lib/python2.7/site-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
    utility.execute()
  File "/Users/stormy/dev/mezz/env/lib/python2.7/site-packages/django/core/management/__init__.py", line 356, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/stormy/dev/mezz/env/lib/python2.7/site-packages/django/core/management/base.py", line 283, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/Users/stormy/dev/mezz/env/lib/python2.7/site-packages/django/core/management/base.py", line 330, in execute
    output = self.handle(*args, **options)
  File "/Users/stormy/dev/mezz/env/lib/python2.7/site-packages/django/core/management/commands/loaddata.py", line 69, in handle
    self.loaddata(fixture_labels)
  File "/Users/stormy/dev/mezz/env/lib/python2.7/site-packages/django/core/management/commands/loaddata.py", line 109, in loaddata
    self.load_label(fixture_label)
  File "/Users/stormy/dev/mezz/env/lib/python2.7/site-packages/django/core/management/commands/loaddata.py", line 175, in load_label
    obj.save(using=self.using)
  File "/Users/stormy/dev/mezz/env/lib/python2.7/site-packages/django/core/serializers/base.py", line 205, in save
    models.Model.save_base(self.object, using=using, raw=True, **kwargs)
  File "/Users/stormy/dev/mezz/env/lib/python2.7/site-packages/django/db/models/base.py", line 848, in save_base
    update_fields=update_fields, raw=raw, using=using,
  File "/Users/stormy/dev/mezz/env/lib/python2.7/site-packages/django/dispatch/dispatcher.py", line 193, in send
    for receiver in self._live_receivers(sender)
  File "/Users/stormy/dev/mezz/env/lib/python2.7/site-packages/mezzanine/generic/fields.py", line 100, in _related_items_changed
    for_model = kwargs["instance"].content_type.model_class()
  File "/Users/stormy/dev/mezz/env/lib/python2.7/site-packages/django/db/models/fields/related_descriptors.py", line 194, in __get__
    "%s has no %s." % (self.field.model.__name__, self.field.name)
django.db.models.fields.related_descriptors.RelatedObjectDoesNotExist: Problem installing fixture '/Users/stormy/dev/mezz/_backups/back_generic_django_comments.json': Comment has no content_type.