'QuerySet' object has no attribute 'set_password'

This error occurs when you try to call a method that is not defined on a QuerySet object. The set_password method is defined on the User object in Django, not on a QuerySet.

To fix this error, you need to make sure that you are calling the set_password method on the correct object. For example, if you want to set the password for a user with a specific username, you would first retrieve the user object from the database using a QuerySet, and then call the set_password method on that user object:

user = User.objects.get(username='example_user')
user.set_password('new_password')
user.save()

Make sure that you are importing the User model from the correct location, which is typically `from django.contrib.auth.models import User`.