我在Django中使用芹菜节拍来安排定期任务的Django == 2.0

如何解决我在Django中使用芹菜节拍来安排定期任务的Django == 2.0

我正在使用Django 2.0版，并尝试使用celery beat安排定期任务。错误如下：

 File "/home/yash/Documents/erp_notify/env/lib/python3.6/site-packages/django/db/models/manager.py",line 82,in manager_method
    return getattr(self.get_queryset(),name)(*args,**kwargs)
  File "/home/yash/Documents/erp_notify/env/lib/python3.6/site-packages/django/db/models/query.py",line 417,in create
    obj.save(force_insert=True,using=self.db)
  File "/home/yash/Documents/erp_notify/env/lib/python3.6/site-packages/django_celery_beat/models.py",line 567,in save
    super(PeriodicTask,self).save(*args,**kwargs)
  File "/home/yash/Documents/erp_notify/env/lib/python3.6/site-packages/django/db/models/base.py",line 729,in save
    force_update=force_update,update_fields=update_fields)
  File "/home/yash/Documents/erp_notify/env/lib/python3.6/site-packages/django/db/models/base.py",line 769,in save_base
    update_fields=update_fields,raw=raw,using=using,File "/home/yash/Documents/erp_notify/env/lib/python3.6/site-packages/django/dispatch/dispatcher.py",line 178,in send
    for receiver in self._live_receivers(sender)
  File "/home/yash/Documents/erp_notify/env/lib/python3.6/site-packages/django/dispatch/dispatcher.py",in <listcomp>
    for receiver in self._live_receivers(sender)
  File "/home/yash/Desktop/er/erp_back/erp/erp/middleware/middleware.py",line 132,in create_user_profile
    if not 'LogRecord' in str(instance):
  File "/home/yash/Documents/erp_notify/env/lib/python3.6/site-packages/django_celery_beat/models.py",line 581,in __str__
    if self.interval:
  File "/home/yash/Documents/erp_notify/env/lib/python3.6/site-packages/django/db/models/fields/related_descriptors.py",line 158,in __get__
    rel_obj = self.field.get_cached_value(instance)
  File "/home/yash/Documents/erp_notify/env/lib/python3.6/site-packages/django/db/models/fields/mixins.py",line 13,in get_cached_value
    return instance._state.fields_cache[cache_name]
AttributeError: 'PeriodicTask' object has no attribute '_state'