How to fix-no such table: main.auth_user__old
first of all you don't have to change your code, the problem your django version
I'm pretty sure that you're following mosh's tutorial or something like that,
to fix this problem follow this steps:

exit the IDE you are using
delete db.sqlite from the folder in your computer not inside the IDE
open your IDE and upgrade your django version using this command pip install --upgrade django==2.1.5
run this command python manage.py makemigrations
then run this command python manage.py migrate
this will help you Enchallah
Can someone give a detailed explanation on how to fix the ERROR: no such table: main.auth_user__old
It arises in my Django application when I am trying to add data to my registered models.