Update primary key Django MySQL

I don't think Django allows you to change the object's primary key. You may have to delete the original object.

e2.delete()

According to the Django docs

The primary key field is read-only. If you change the value of the primary key on an existing object and then save it, a new object will be created alongside the old one.

Django Docs

Django's Model.save() method relies on whether there's already a row with the same PK in your db to decide if it should issue an INSERT or UPDATE query.

As a more general rule: while it's technically possible to modify a PK at the SQL level, it's no necessarily such a good idea, as it means you'd have to update all related rows in all related tables (ok, still technically possible but really not a sane idea as far as I'm concerned), AND warn all applications depending on this PK of the change too - and then good luck. To make a long story short: it's always safer to consider PKs as immutable (and that's why quite a few people in the SQL world favor surrogate primary keys even when there's a seemingly obvious natural one).