diff --git a/README.rst b/README.rst
index a10f428..a11bb89 100644
--- a/README.rst
+++ b/README.rst
@@ -66,6 +66,10 @@ You must install the following packages to use Mandaye
 
     From sources: http://pypi.python.org/pypi/lxml
 
+ * xtraceback 0.3::
+
+    From sources: http://pypi.python.org/pypi/xtraceback
+
 You can install all those dependencies quickly using pip::
 
    pip install gevent poster SQLAlchemy Beaker Mako lxml
diff --git a/mandaye/response.py b/mandaye/response.py
index 1f9af1d..227dc52 100644
--- a/mandaye/response.py
+++ b/mandaye/response.py
@@ -1,6 +1,7 @@
-
 import logging
-import traceback
+import xtraceback
+import pprint
+import sys
 
 from cgi import escape
 
@@ -10,10 +11,12 @@ from mandaye.config import debug
 from template import serve_template
 
 
-def _get_html_traceback(exception, path):
-    tb_str = traceback.format_exc()
-    msg = "<h2>%s %s</h2><pre>%s</pre>" % \
-            (path, exception, escape(tb_str))
+def _get_html_traceback(tb_str, path, env=None):
+    msg = "<h2>%s</h2><h3>Exception</h3><pre>%s</pre>" % \
+            (path, escape(tb_str))
+    if env:
+        env = pprint.pformat(env)
+        msg += '<h3>Environment</h3><pre>%s</pre>' % escape(env)
     return msg
 
 def _302(location, cookies=None):
@@ -37,17 +40,20 @@ def _404(path):
     return HTTPResponse(404, 'Not found', headers,
             serve_template("response.html", title=title, body=body))
 
-def _500(path, msg, exception=None):
+def _500(path, msg, exception=None, env=None):
     """ Return a 500 error
     path: the path of this error
     exception: this exception instance if any """
-    logging.critical("500 %s: %s" % (path, msg))
+    if exception:
+        tb_str = str(xtraceback.XTraceback(*sys.exc_info(), color=False))
+        logging.exception("500 %s: %s, %s, env: %r" % (path, msg, tb_str, env))
+    else:
+        logging.error("500 %s: %s, env: %r" % (path, msg, env))
     title = 'Internal Server Error'
     headers = HTTPHeader({'Content-Type': ['text/html']})
     if debug:
         if exception:
-            traceback.print_exc()
-            msg += _get_html_traceback(exception, path)
+            msg += _get_html_traceback(tb_str, path, env=env)
         else:
             msg=msg
     else:
diff --git a/mandaye/server.py b/mandaye/server.py
index 17a632d..b89eed8 100644
--- a/mandaye/server.py
+++ b/mandaye/server.py
@@ -82,6 +82,7 @@ class MandayeApp(object):
         env: standard WSGI env
         start_response: stanard WSGI / CGI function
         """
+        response = []
         try:
             self.env = env
             self.env['mandaye.scheme'] = env['wsgi.url_scheme']
@@ -99,18 +100,20 @@ class MandayeApp(object):
                         elif mapper.has_key('static'):
                             env['PATH_INFO'] = re.sub('^' + mapper.get('path'), '',
                                     env['PATH_INFO'])
-                            return Cling(mapper.get('static')).__call__(env, start_response)
-            if self.dispatcher:
-                return self.on_request(start_response)
-            else:
-                return self.on_response(start_response, _404(env['PATH_INFO']))
-        except Exception, e:
-            logging.exception('WSGI handler thrown an exception')
-            sql_session.rollback()
-        else:
+                            response = Cling(mapper.get('static')).__call__(env, start_response)
+            if not response:
+                if self.dispatcher:
+                    response = self.on_request(start_response)
+                else:
+                    response = self.on_response(start_response, _404(env['PATH_INFO']))
             sql_session.commit()
+        except Exception, e:
+            sql_session.rollback()
+            response = self.on_response(start_response, _500(env['PATH_INFO'], "Unhandled exception",
+                exception=e, env=env))
         finally:
             sql_session.close()
+        return response
 
 
     def _get_request(self):