[Answered ]-Decouple module error running Django 1.8 project using Django 1.9

It is not because you use Django 1.9 that you get that error, it is because that module is not install at the moment. Run pip install python-decouple to install the module.

In my case installing python-decouple also outside the vitualenv solved the problem.

comp@debian:~/Desktop/prj$sudo pip install python-decouple
(venv) comp@debian:~/Desktop/prj$pip install python-decouple