diff --git a/api/front_msg_processer.cpp b/api/front_msg_processer.cpp
index c7f1ef2..027acbc 100644
--- a/api/front_msg_processer.cpp
+++ b/api/front_msg_processer.cpp
@@ -1,4 +1,5 @@
 #include "front_msg_processer.hpp"
+#include "iflytop/core/error/error_code.hpp"
 
 using namespace iflytop;
 
@@ -9,7 +10,7 @@ void FrontMsgProcesser::processMsg(json& cmd, json& receipt) {
     m_msgProcesserMap[cmdstr](cmd, receipt);
   } else {
     logger->error("unknown command: {}", cmdstr);
-    receipt["result"] = "error";
+    receipt["ackcode"]   = err::kfail;
     receipt["reason"] = "unknown command";
   }
 }