When setting up Rhode code as described here: http://packages.python.org/RhodeCode/setup.html#setup
They are some very strange errors. First Apache frequently send a 500-Internal server error. This is triggered by the file site-packages/paste/evalexception :
assert not environ['wsgi.multiprocess'],
"The EvalException middleware is not usable in a"
The solution MAY be to not set processes=1 in the WSGIDaemonProcess.
quoting http://code.google.com/p/modwsgi/wiki/ConfigurationDirectives#WSGIDaemonProcess: Note that if this option is defined as 'processes=1', then the WSGI environment attribute called 'wsgi.multiprocess' will be set to be True whereas not providing the option at all will result in the attribute being set to be False. This distinction is to allow for where some form of mapping mechanism might be used to distribute requests across multiple process groups and thus in effect it is still a multiprocess application. If you need to ensure that 'wsgi.multiprocess' is False so that interactive debuggers will work, simply do not specify the 'processes' option and allow the default single daemon process to be created in the process group.