Why is primary_key not editable in django?

Question

Django

Available model

class TreeNode(MPTTModel):
    id = models.CharField(max_length=10, primary_key=True)
    itn = models.CharField(max_length=40, unique=True)

When trying to edit the id, it says that a TreeNode with this itn already exists, although it has not been edited. itn is edited without problems. What's the matter?

Answer 1

The primary key is not meant to be edited at all, and no one expects you to edit it. Any side effects may appear. Why do you need it?