I set an incorrect value for 'idp storage path' and the plugin failed to configure but it still attempted to serve SAML2 requests, failing with a 500 error:

[Wed Aug 26 11:06:56.885840 2015] [wsgi:error] [pid 32623] [26/Aug/2015:11:06:56] DEBUG(ipsilon/providers/common.py:93 Redirect.debug()): saml2: 'NoneType' object has no attribute 'get_login_handler'
[Wed Aug 26 11:06:56.888788 2015] [wsgi:error] [pid 32623] [26/Aug/2015:11:06:56] DEBUG(ipsilon/util/errors.py:18 Errors.handler()): ['500 Internal Server Error', 'The server encountered an unexpected condition which prevented it from fulfilling the request.', 'Traceback (most recent call last): File "/usr/lib/python2.7/site-packages/cherrypy/_cprequest.py", line 656, in respond response.body self.oldhandler(args, kwargs) File "/usr/lib/python2.7/site-packages/cherrypy/_cpdispatch.py", line 34, in call return self.callable(*self.args, self.kwargs) File "/usr/lib/python2.7/site-packages/ipsilon/util/page.py", line 91, in call return op(args, kwargs) File "/usr/lib/python2.7/site-packages/ipsilon/providers/common.py", line 87, in root return op(*args, kwargs) File "/usr/lib/python2.7/site-packages/ipsilon/providers/saml2idp.py", line 79, in GET login = self.saml2login(query) File "/usr/lib/python2.7/site-packages/ipsilon/providers/saml2/auth.py", line 118, in saml2login raise cherrypy.HTTPError(500)HTTPError: (500, None)', '3.2.2']

It also tracebacks if the certificate or key cannot be loaded.