diff --git a/ldapcherry/__init__.py b/ldapcherry/__init__.py
index e8cd9c2..409281b 100644
--- a/ldapcherry/__init__.py
+++ b/ldapcherry/__init__.py
@@ -43,7 +43,7 @@
         ):
 
     if traceback and msg == '':
-        msg = 'python exception'
+        msg = 'Python Exception:'
     if context == '':
         cherrypy.log.error_log.log(severity, msg)
     else:
@@ -51,8 +51,8 @@
             severity,
             ' '.join((context, msg))
             )
-    import traceback
     if traceback:
+        import traceback
         try:
             exc = sys.exc_info()
             if exc == (None, None, None):
@@ -65,6 +65,28 @@
             del exc
 
 
+def exception_decorator(func):
+    def ret(self, *args, **kwargs):
+        try:
+            return func(self, *args, **kwargs)
+        except cherrypy.HTTPRedirect as e:
+            raise e
+        except cherrypy.HTTPError as e:
+            raise e
+        except Exception as e:
+            self._handle_exception(e)
+            username = self._check_session()
+            if not username:
+                return self.temp_service_unavailable.render()
+            is_admin = self._check_admin()
+            return self.temp_error.render(
+                is_admin=is_admin,
+                alert='danger',
+                message="An error occured, please check logs for details"
+                )
+    return ret
+
+
 class LdapCherry(object):
 
     def _handle_exception(self, e):
@@ -75,7 +97,7 @@
             )
         else:
             cherrypy.log.error(
-                msg="unkwon exception: '%(e)s'" % {'e': str(e)},
+                msg="uncatched exception: [%(e)s]" % {'e': str(e)},
                 severity=logging.ERROR
             )
         # log the traceback as 'debug'
@@ -407,6 +429,8 @@
             self.temp_lookup.get_template('selfmodify.tmpl')
         self.temp_modify = \
             self.temp_lookup.get_template('modify.tmpl')
+        self.temp_service_unavailable = \
+            self.temp_lookup.get_template('service_unavailable.tmpl')
 
     def reload(self, config=None):
         """ load/reload configuration
@@ -543,6 +567,11 @@
             return True
         return cherrypy.session['isadmin']
 
+    def _check_session(self):
+        if self.auth_mode == 'none':
+            return 'anonymous'
+        username = cherrypy.session.get(SESSION_KEY)
+
     def _check_auth(self, must_admin):
         """ check if a user is autheticated and, optionnaly an administrator
         if user not authentifaced -> redirection to login page (with base64
@@ -554,7 +583,7 @@
         """
         if self.auth_mode == 'none':
             return 'anonymous'
-        username = cherrypy.session.get(SESSION_KEY)
+        username = self._check_session() 
 
         if cherrypy.request.query_string == '':
             qs = ''
@@ -812,12 +841,14 @@
         return self.ppolicy.check(password)
 
     @cherrypy.expose
+    @exception_decorator
     def signin(self, url=None):
         """simple signin page
         """
         return self.temp_login.render(url=url)
 
     @cherrypy.expose
+    @exception_decorator
     def login(self, login, password, url=None):
         """login page
         """
@@ -861,6 +892,7 @@
             raise cherrypy.HTTPRedirect("/signin" + qs)
 
     @cherrypy.expose
+    @exception_decorator
     def logout(self):
         """ logout page
         """
@@ -877,6 +909,7 @@
         raise cherrypy.HTTPRedirect("/signin")
 
     @cherrypy.expose
+    @exception_decorator
     def index(self):
         """main page rendering
         """
@@ -885,6 +918,7 @@
         return self.temp_index.render(is_admin=is_admin)
 
     @cherrypy.expose
+    @exception_decorator
     def searchuser(self, searchstring=None):
         """ search user page """
         self._check_auth(must_admin=False)
@@ -901,6 +935,7 @@
             )
 
     @cherrypy.expose
+    @exception_decorator
     def checkppolicy(self, **params):
         """ search user page """
         keys = params.keys()
@@ -918,6 +953,7 @@
         return json.dumps(ret, separators=(',', ':'))
 
     @cherrypy.expose
+    @exception_decorator
     def searchadmin(self, searchstring=None):
         """ search user page """
         self._check_auth(must_admin=True)
@@ -934,6 +970,7 @@
             )
 
     @cherrypy.expose
+    @exception_decorator
     def adduser(self, **params):
         """ add user page """
         self._check_auth(must_admin=True)
@@ -979,6 +1016,7 @@
             )
 
     @cherrypy.expose
+    @exception_decorator
     def delete(self, user):
         """ remove user page """
         self._check_auth(must_admin=True)
@@ -988,6 +1026,7 @@
         raise cherrypy.HTTPRedirect(referer)
 
     @cherrypy.expose
+    @exception_decorator
     def modify(self, user=None, **params):
         """ modify user page """
         self._check_auth(must_admin=True)
@@ -1042,6 +1081,7 @@
             )
 
     @cherrypy.expose
+    @exception_decorator
     def selfmodify(self, **params):
         """ self modify user page """
         self._check_auth(must_admin=False)
diff --git a/ldapcherry/exceptions.py b/ldapcherry/exceptions.py
index d91d0fc..c249d76 100644
--- a/ldapcherry/exceptions.py
+++ b/ldapcherry/exceptions.py
@@ -184,3 +184,23 @@
         self.attr = attr
         self.log = \
             "attribute '" + attr + "' is not defined in configuration"
+
+
+class UserDoesntExist(Exception):
+    def __init__(self, user, backend):
+        self.user = user
+        self.bakend = backend
+        self.log = \
+            "user '" + user + "'" \
+            " does not exist" \
+            " in backend '" + backend + "'"
+
+
+class GroupDoesntExist(Exception):
+    def __init__(self, group, backend):
+        self.group = group
+        self.bakend = backend
+        self.log = \
+            "group '" + group + "'" \
+            " does not exist" \
+            " in backend '" + backend + "'"
diff --git a/resources/templates/service_unavailable.tmpl b/resources/templates/service_unavailable.tmpl
new file mode 100644
index 0000000..7d706d2
--- /dev/null
+++ b/resources/templates/service_unavailable.tmpl
@@ -0,0 +1,16 @@
+## -*- coding: utf-8 -*-
+<%inherit file="base.tmpl"/>
+<%block name="core">
+    <div class="row clearfix" style="margin-top:30px">
+        <div class="col-md-4 column"></div>
+        <div class="col-md-4 column well">
+        <div class="alert alert-dismissable alert-danger">
+            <h4>
+                Service Unavailable
+            </h4>
+        </div>
+        <a class="btn btn-default blue" href='/signin'><span class="glyphicon glyphicon-home"></span> Return</a>
+        </div>
+        <div class="col-md-4 column"></div>
+    </div>
+</%block>