diff --git a/cpp/protoutils.cc b/cpp/protoutils.cc
index bc7c800..d5a6157 100644
--- a/cpp/protoutils.cc
+++ b/cpp/protoutils.cc
@@ -108,7 +108,7 @@ namespace f8
         head->msgid = msgid;
         head->seqid = seqid;
         head->magic_code = MAGIC_CODE;
-        head->rpc_error_code = 0;
+        head->ext_len = 0;
         msg.SerializeToArray(buff + sizeof(PackHead), packlen);
         tcp_client->SendBuff(buff, sizeof(PackHead) + packlen);
         free(buff);