How to upgrade django?
From the Django Docs: if you are using a Virtual Environment and it is a major upgrade, you might want to set up a new environment with the dependencies first.
Or, if you have installed Django using the PIP, then the below is for you:
python3.8 -m pip install -U Django .
My project was running on Django 1.5.4 and I wanted to upgrade it. I did pip install -U -I django and now pip freeze shows Django 1.6.5 (clearly django has upgraded, I'm in virtualenv) but my project is still using Django 1.5.4. How can I use the upgraded version? 
UPDATE: Thanks for your comments. I tried everything but unfortunately nothing worked and I had to re-deploy the app.
Hope someone explains why this happened.