diff --git a/ryu/controller/ofp_handler.py b/ryu/controller/ofp_handler.py
index 4f439c2e..3f4d2be9 100644
--- a/ryu/controller/ofp_handler.py
+++ b/ryu/controller/ofp_handler.py
@@ -60,11 +60,11 @@ class OFPHandler(ryu.base.app_manager.RyuApp):
         return hub.spawn(self.controller)
 
     def _hello_failed(self, datapath, error_desc):
-        self.logger.error(error_desc)
+        self.logger.error('%s %r', error_desc, datapath.address)
         error_msg = datapath.ofproto_parser.OFPErrorMsg(datapath)
         error_msg.type = datapath.ofproto.OFPET_HELLO_FAILED
         error_msg.code = datapath.ofproto.OFPHFC_INCOMPATIBLE
-        error_msg.data = error_desc
+        error_msg.data = error_desc.encode('ascii')
         datapath.send_msg(error_msg)
 
     @set_ev_handler(ofp_event.EventOFPHello, HANDSHAKE_DISPATCHER)