嗨，我在迁移时遇到问题，我想帮助我查看了所有无法找出解决方案的模型
Applying accounts.0013_add_primary_interests...Traceback (most recent call last):
File "manage.py", line 22, in <module>
execute_from_command_line(sys.argv)
File "/Users/mumirahibrahim/Library/Python/3.6/lib/python/site-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
utility.execute()
File "/Users/mumirahibrahim/Library/Python/3.6/lib/python/site-packages/django/core/management/__init__.py", line 356, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/Users/mumirahibrahim/Library/Python/3.6/lib/python/site-packages/django/core/management/base.py", line 283, in run_from_argv
self.execute(*args, **cmd_options)
File "/Users/mumirahibrahim/Library/Python/3.6/lib/python/site-packages/django/core/management/base.py", line 330, in execute
output = self.handle(*args, **options)
File "/Users/mumirahibrahim/Library/Python/3.6/lib/python/site-packages/django/core/management/commands/migrate.py", line 204, in handle
fake_initial=fake_initial,
File "/Users/mumirahibrahim/Library/Python/3.6/lib/python/site-packages/django/db/migrations/executor.py", line 115, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
File "/Users/mumirahibrahim/Library/Python/3.6/lib/python/site-packages/django/db/migrations/executor.py", line 145, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "/Users/mumirahibrahim/Library/Python/3.6/lib/python/site-packages/django/db/migrations/executor.py", line 244, in apply_migration
state = migration.apply(state, schema_editor)
File "/Users/mumirahibrahim/Library/Python/3.6/lib/python/site-packages/django/db/migrations/migration.py", line 129, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/Users/mumirahibrahim/Library/Python/3.6/lib/python/site-packages/django/db/migrations/operations/special.py", line 193, in database_forwards
self.code(from_state.apps, schema_editor)
File "/Users/mumirahibrahim/Desktop/mo/Fudulbank/accounts/migrations/0013_add_primary_interests.py", line 14, in add_primary_interests
exam_content_type = ContentType.objects.get(app_label='exams', model='exam')
File "/Users/mumirahibrahim/Library/Python/3.6/lib/python/site-packages/django/db/models/manager.py", line 85, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/Users/mumirahibrahim/Library/Python/3.6/lib/python/site-packages/django/db/models/query.py", line 380, in get
self.model._meta.object_name
__fake__.DoesNotExist: ContentType matching query does not exist.
请帮助我