If you have Google App Engine installed via the official Mac launcher, and you also have Python installed under Macports, you might forget and try to run your app server via the Macports Python. This results in the following error:

'module' object has no attribute 'HTTPSHandler'

Simply change your environment to use the system Python with python_select python25-apple and issue the ./manage.py runserver command to kick things off again.

The Macports Python Google App Engine Gotcha article by Aral Balkan, unless otherwise expressly stated, is licensed under a Creative Commons Attribution-Noncommercial 2.0 UK: England License.