This has robbed me of several days of my life, so I want to bring Google juice this this problem.

IF you have a Pylons or TurboGears application or anything else that uses the fantastic EvalException WSGI middleware for web debugging of you web program and have the following symptom:

* on a crash the traceback page shows up, but it has no css style and no images
* returns a 404 (where is the path of your application) with "Nothing could be found to match '_debug'"

The problem that you are facing in this case is the enviroment variable PYTHONOPTIMIZE or apache_wsgi option WSGIPythonOptimize. Unset them both or you debug environment will not work!