Uprading to Django 5.2 from Django 5.1.7 creates a new migration for a self referencing through model

[Mark Chackerian]

I have a model with a self-referential through model like

class Cad((models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    cads: models.ManyToManyField = models.ManyToManyField(
        "self", symmetrical=False, through="CadChild", through_fields=("parent", "child")
    )
   ...

class CadChild(models.Model):
    """A through model for Cad parent/child many-to-many relationships."""

    parent = models.ForeignKey(
        Cad,
        on_delete=models.CASCADE,
        related_name="parent_cad_set",
    )
    child = models.ForeignKey(
        Cad,
        on_delete=models.CASCADE,
        related_name="child_cad_set",
    )

When I upgraded from 5.1.7 to 5.2 I needed to created to create a new migration, which looked like:

# Generated by Django 5.2 on 2025-04-21 13:25

from django.db import migrations, models




class Migration(migrations.Migration):

    dependencies = [
        ('projects', '0012_documentpagetheme_documentpagethemeuserdefault'),
    ]

    operations = [
        migrations.AlterField(
            model_name='cad',
            name='cads',
            field=models.ManyToManyField(through='projects.CadChild', through_fields=('parent', 'child'), to='projects.cad'),
        ),
    ]

---

This may be intended behavior but I can't find any reference to this change in the release notes.

[Simon Charette]

Thank you for your report, it is effectively intended.

Prior to Django 5.2 there was a bug that prevented the appropriate tracking of through_fields in migrations #36061 (b13b8684a04d0bc1081104c5973c62c27dc673b0) which could cause crashes or data corruptions if the involved models were used in data migrations (e.g. through RunPython). You'll notice that the migration defining cads will be lacking the through_fields you declared in your models.

We don't document bug fixes in release notes hence why you couldn't find it.