a django CMS version 3 database. This can lead to corruption since the data structures for the CMSPlugin models are different. Warning Do not add CMS_CONFIRM_VERSION4 = True to your django CMS version class; these all inherit from the cms.models.pluginmodel.CMSPlugin base class. Note django CMS plugins inherit from cms.models.pluginmodel.CMSPlugin (or a sub- class thereof) and not models.Model [https://docs plugin class: from django.db import models from cms.models import CMSPlugin from polls.models import Poll class PollPluginModel(CMSPlugin): poll = models.ForeignKey(Poll, on_delete=models.CASCADE)