[Answered ]-Django.db.utils.ProgrammingError: multiple default values specified for column "id" of table "products_customer"

I think you get this error because you try to make the migrations on a non-existent database table.

Try to delete everything from the migrations folder (except __init__.py), and delete the .sqlite3 database file as well, then rerun

python manage.py makemigrations

python manage.py migrate

Be aware, this will delete your database and your migrations so far!

But most likely it will fix your issue.