Fixing on_delete in models or switch from functions to properties in User model will be more complicated.Of course you can start monkey patching the libraries, but this is not a solution I would recommend, as it will only bring messy stuff to the code and it does not really solve the issue for future applications.The best approach would be to find the package repository on Github and make a Fork of it, where you can do all the changes required to make the application run with Django 2.0.
For the second issue above, I found a solution which allows the usage of the package in a Django 2.0 application.
But, It’s always recommended to upgrade the Django applications to newer versions.
I recently upgraded a Django app we had on Django 1.6 to Django 1.11. This article was written by Anjaneyulu on Apr 12, 2018 in python , django , version-upgrade . We love building amazing apps for web and mobile for our clients.
Keeping dependencies updated is crucial to the project's health.
Newer package version close bugs, fix security issues and bring new feature sets from which applications can benefit.