nginx + uwsgi: -- unavailable modifier requested: 0 --

Original answer

For Python 2 on Ubuntu 11.10, using upstart, install the python plugin for uWSGI with apt-get install uwsgi-plugin-python and if you're using an ini file to configure your uWSGI app, then add plugins = python to the [uwsgi] section and it should solve this problem.

Edit: Updated for Python 3 and Ubuntu 17.10

For Python 3 on Ubuntu 17.10, using systemd, install the python plugin for uWSGI with apt-get install uwsgi-plugin-python3 and if you're using an ini file to configure your uWSGI app, then add plugins = python to the [uwsgi] section and it should solve this problem.

For more information on getting started with python/uWSGI apps, including how to configure them using an ini file then please take a look at this handy guide

Solved by installing uwsgi-plugin-python3 plugin and adding --plugin python3 option to uwsgi start command

Im starting uwsgi from upstart on Ubuntu. I solved the problem by running apt-get install uwsgi-plugin-python, and then adding plugins=python to my application.ini in /etc/uwsgi/applications-available.