diff --git a/rskj-core/src/main/java/co/rsk/rpc/netty/JsonRpcCustomServer.java b/rskj-core/src/main/java/co/rsk/rpc/netty/JsonRpcCustomServer.java
index 4161e4a1255..58559b9ea70 100644
--- a/rskj-core/src/main/java/co/rsk/rpc/netty/JsonRpcCustomServer.java
+++ b/rskj-core/src/main/java/co/rsk/rpc/netty/JsonRpcCustomServer.java
@@ -107,13 +107,12 @@ private Set<String> extractMethodNames(Class<?> remoteInterface) {
     }
 
     private JsonResponse buildError(Object id, int errorCode, String errorMessage) {
-        ObjectMapper mapper = new ObjectMapper();
-        ObjectNode response = mapper.createObjectNode();
+        ObjectNode response = objectMapper.createObjectNode();
         response.put(JSONRPC, VERSION);
         if(id != null) {
-            response.set(ID, mapper.valueToTree(id));
+            response.set(ID, objectMapper.valueToTree(id));
         }
-        ObjectNode error = mapper.createObjectNode();
+        ObjectNode error = objectMapper.createObjectNode();
         error.put(ERROR_CODE, errorCode);
         error.put(ERROR_MESSAGE, errorMessage);