diff --git a/thirdpart/shibboleth/middleware.py b/thirdpart/shibboleth/middleware.py
index 9309edaa11..64af3a1405 100755
--- a/thirdpart/shibboleth/middleware.py
+++ b/thirdpart/shibboleth/middleware.py
@@ -18,19 +18,22 @@ from seahub.base.accounts import User
 from seahub.base.sudo_mode import update_sudo_mode_ts
 from seahub.profile.models import Profile
 from seahub.utils.file_size import get_quota_from_string
-from seahub.utils.user_permissions import get_user_role
 
 # Get an instance of a logger
 logger = logging.getLogger(__name__)
 
-conf_dir = os.environ['SEAFILE_CENTRAL_CONF_DIR']
-sys.path.append(conf_dir)
 try:
-    from seahub_custom_functions import custom_shibboleth_get_user_role
-    CUSTOM_SHIBBOLETH_GET_USER_ROLE = True
-except ImportError as e:
+    conf_dir = os.environ['SEAFILE_CENTRAL_CONF_DIR']
+    sys.path.append(conf_dir)
+    try:
+        from seahub_custom_functions import custom_shibboleth_get_user_role
+        CUSTOM_SHIBBOLETH_GET_USER_ROLE = True
+    except ImportError:
+        CUSTOM_SHIBBOLETH_GET_USER_ROLE = False
+except KeyError:
     CUSTOM_SHIBBOLETH_GET_USER_ROLE = False
 
+
 class ShibbolethRemoteUserMiddleware(RemoteUserMiddleware):
     """
     Authentication Middleware for use with Shibboleth.  Uses the recommended pattern
@@ -52,15 +55,15 @@ class ShibbolethRemoteUserMiddleware(RemoteUserMiddleware):
                 " 'django.contrib.auth.middleware.AuthenticationMiddleware'"
                 " before the RemoteUserMiddleware class.")
 
-        #To support logout.  If this variable is True, do not
-        #authenticate user and return now.
+        # To support logout.  If this variable is True, do not
+        # authenticate user and return now.
         if request.session.get(LOGOUT_SESSION_KEY) is True:
             return
         else:
-            #Delete the shib reauth session key if present.
+            # Delete the shib reauth session key if present.
             request.session.pop(LOGOUT_SESSION_KEY, None)
 
-        #Locate the remote user header.
+        # Locate the remote user header.
         # import pprint; pprint.pprint(request.META)
         try:
             username = request.META[SHIB_USER_HEADER]
@@ -119,7 +122,7 @@ class ShibbolethRemoteUserMiddleware(RemoteUserMiddleware):
             if user_role:
                 self.update_user_quota(user, user_role)
 
-            #setup session.
+            # setup session.
             self.setup_session(request)
             request.shib_login = True
 
@@ -253,5 +256,6 @@ class ShibbolethRemoteUserMiddleware(RemoteUserMiddleware):
                     error = True
         return shib_attrs, error
 
+
 class ShibbolethValidationError(Exception):
     pass