Invalid model reference ‘my.guru.Comment_ref_comments’. String model references must be of the form ‘app_label.ModelName’

I've got this problem here. I will paste in my code too. After looking through the internet, I found this error, but only for custom user models.

In my example I have a simple Comment model:

class Comment(models.Model):    author = models.ForeignKey(User, default=1, on_delete=models.SET_DEFAULT)    published = models.DateField(auto_now_add=True)    hidden = models.BooleanField(default=False)    content = models.TextField()    ref_comments = models.ManyToManyField('self', blank=True, related_name="comment_relation", default=None)    parent = models.ForeignKey('self', default=None, null=True, on_delete=models.SET_DEFAULT)    level = models.SmallIntegerField(default=1)    no_of_reactions = models.IntegerField(default=0)    def delete_tread(self):        self.delete()        orphans = Comment.objects.filter(parent=None)        for com in orphans:            if not com.get_blog() and not com.get_vlog() and not com.get_popPost() and not com.get_article():                com.delete()    def get_article(self):        if self.article_relation.all():            return self.article_relation.all()[0]        else:            return None    def get_blog(self):        if self.blog_relation.all():            return self.blog_relation.all()[0]        else:            return None    def get_vlog(self):        if self.vlog_relation.all():            return self.vlog_relation.all()[0]        else:            return None    def get_popPost(self):        if self.pop_relation.all():            return self.pop_relation.all()[0]        else:            return None    def __str__(self):        return self.content

Error message:

File “/workspaces/coachGu-live/guru/models.py”, line 100, inclass Comment(models.Model):File “/usr/local/python/3.10.13/lib/python3.10/site-packages/django/db/models/base.py”, line 160, in newnew_class.add_to_class(obj_name, obj)File “/usr/local/python/3.10.13/lib/python3.10/site-packages/django/db/models/base.py”, line 325, in add_to_classvalue.contribute_to_class(cls, name)File “/usr/local/python/3.10.13/lib/python3.10/site-packages/django/db/models/fields/related.py”, line 1585, in contribute_to_classself.remote_field.through = create_many_to_many_intermediary_model(self, cls)File “/usr/local/python/3.10.13/lib/python3.10/site-packages/django/db/models/fields/related.py”, line 1052, in create_many_to_many_intermediary_modellazy_related_operation(set_managed, klass, to_model, name)File “/usr/local/python/3.10.13/lib/python3.10/site-packages/django/db/models/fields/related.py”, line 80, in lazy_related_operationreturn apps.lazy_model_operation(partial(function, **kwargs), *model_keys)File “/usr/local/python/3.10.13/lib/python3.10/site-packages/django/db/models/fields/related.py”, line 78, inmodel_keys = (make_model_tuple(m) for m in models)File “/usr/local/python/3.10.13/lib/python3.10/site-packages/django/db/models/utils.py”, line 18, in make_model_tupleraise ValueError(ValueError: Invalid model reference ‘my.guru.Comment_ref_comments’. String model references must be of the form ‘app_label.ModelName’.

Please help me, and tell if I need to show other code snippets!

I tried to find a solution on the internet, and nothing helped