diff --git a/sjrpc/client/simple.py b/sjrpc/client/simple.py
index d4586f19e89d00280f806e09f1f9822c103216d5..cd8477e88020781ef75611e0c81df81eea211b4b 100644
--- a/sjrpc/client/simple.py
+++ b/sjrpc/client/simple.py
@@ -84,7 +84,7 @@ class SimpleRpcClient(ConnectionManager):
                 self._connection.receive()
             except socket.error as err:
                 logging.error('Socket error while receiving from the client '
-                              'fd/%s: %s' % (fd, err))
+                              'fd/%s: %s', fd, err)
                 self.shutdown()
 
         if event & select.EPOLLOUT:
@@ -93,11 +93,11 @@ class SimpleRpcClient(ConnectionManager):
                 self._connection.send()
             except socket.error as err:
                 logging.error('Socket error while sending to the client '
-                              'fd/%s: %s' % (fd, err))
+                              'fd/%s: %s', fd, err)
                 self.shutdown()
 
         if event & select.EPOLLHUP:
-            logging.error('Socket HUP fd/%s' % fd)
+            logging.error('Socket HUP fd/%s', fd)
             self.shutdown()                                                      #TODO
 
     def all_connections(self):
diff --git a/sjrpc/core/rpcconnection.py b/sjrpc/core/rpcconnection.py
index cf9153baefeaaf11b075bd811a20753098197c8c..222bb657637ba9bdb8758c159341c5bcbbced888 100644
--- a/sjrpc/core/rpcconnection.py
+++ b/sjrpc/core/rpcconnection.py
@@ -149,7 +149,7 @@ class RpcConnection(object):
             payload = self._inbound_buffer.pull(self._cur_msg_size)
             self._cur_msg_size = None
             message = json.loads(payload)
-            logging.debug('Received: %s' % message)
+            logging.debug('Received: %s', message)
             self.dispatch(message)
             return True
 
@@ -164,7 +164,7 @@ class RpcConnection(object):
            Message must be a jsonisable structure.
         '''
 
-        logging.debug('Sending: %s' % message)
+        logging.debug('Sending: %s', message)
         json_msg = json.dumps(message)
         size = struct.pack('!L', len(json_msg))
         with self._outbound_buffer:
@@ -224,7 +224,7 @@ class RpcConnection(object):
         
         self._send_response(msg_id, returned=returned)
     
-    def error(self, msg_id, error, message):
+    def error(self, msg_id, error, message, traceback=None):
         '''
         Send an error response to the peer.
         
@@ -363,7 +363,7 @@ class RpcConnection(object):
                     # manager while cleanup.
 
         else:
-            logging.warning('Malformed message received: %s' % message)
+            logging.warning('Malformed message received: %s', message)
     
     def shutdown(self, callback=None):
         '''
@@ -401,7 +401,7 @@ class RpcConnection(object):
                 callback(self)
             except Exception as err:
                 logging.error('Error while execution of shutdown '
-                              'callback: %s' % err)
+                              'callback: %s', err)
 
     def clean_call(self, msg_id):
         '''
diff --git a/sjrpc/server/simple.py b/sjrpc/server/simple.py
index be5fd88c6950769d6595219cb9c79af7280b4968..8f8c1d5d1d90f8c9a22f980f8d88b50bd0f91c67 100644
--- a/sjrpc/server/simple.py
+++ b/sjrpc/server/simple.py
@@ -79,11 +79,11 @@ class SimpleRpcServer(ConnectionManager):
                     connection.receive()
                 except socket.error as err:
                     logging.error('Socket error while receiving from client '
-                                  'fd/%s: %s' % (fd, err))
+                                  'fd/%s: %s', fd, err)
                     self.shutdown_client(fd)
                 except Exception as err:
                     logging.error('Unknown error while receiving from client '
-                                  'fd/%s: %s' % (fd, err))
+                                  'fd/%s: %s', fd, err)
                     self.shutdown_client(fd)
                 
             if event & select.EPOLLOUT:
@@ -92,15 +92,15 @@ class SimpleRpcServer(ConnectionManager):
                     connection.send()
                 except socket.error as err:
                     logging.error('Socket error while sending to the client '
-                                  'fd/%s: %s' % (fd, err))
+                                  'fd/%s: %s', fd, err)
                     self.shutdown_client(fd)
                 except Exception as err:
                     logging.error('Unknown error while sending to the client '
-                                  'fd/%s: %s' % (fd, err))
+                                  'fd/%s: %s', fd, err)
                     self.shutdown_client(fd)
 
             if event & select.EPOLLHUP:
-                logging.error('Socket HUP fd/%s' % fd)
+                logging.error('Socket HUP fd/%s', fd)
                 self.shutdown_client(fd)
 
 
@@ -129,6 +129,6 @@ class SimpleSslRpcServer(SimpleRpcServer):
                                       ssl_version=ssl.PROTOCOL_TLSv1,
                                       do_handshake_on_connect=True)
         except ssl.SSLError as err:
-            logging.error('Error when accepting ssl connection: %s' % err)
+            logging.error('Error when accepting ssl connection: %s', err)
         else:
             return sslsock, address