diff --git a/api/api.proto b/api/api.proto
index d66ea47ca8a..6763ac506b1 100644
--- a/api/api.proto
+++ b/api/api.proto
@@ -300,12 +300,19 @@ service Database {
 message Return {
   enum response_code {
     SUCCESS = 0;
+    SIGERROR = 1; // error in signature
+    CONTRACT_VALIDATE_ERROR = 2;
+    CONTRACT_EXE_ERROR = 3;
+    BANDWITH_ERROR = 4;
+    DUP_TRANSACTION_ERROR = 5;
+    TAPOS_ERROR = 6;
+    TOO_BIG_TRANSACTION_ERROR = 7;
+    OTHER_ERROR = 20;
   }
 
   bool result = 1;
   response_code code = 2;
   bytes message = 3;
-
 }
 
 message BlockReference {