Installed Virtualenv and activating virtualenv doesn't work
I had installed Django 2 via pip3 install Django, but I was running python manage.py runserver instead of python3 manage.py runserver. Django 2 only works with python 3+.
I cloned my Django Project from Github Account and activated the virtualenv using famous command source nameofenv/bin/activate
And when I run python manage.py runserver 
It gives me an error saying:

ImportError: Couldn't import Django. Are you sure it's installed and available on your PYTHONPATH environment variable? Did you forget to activate a virtual environment?