diff --git a/src/main/java/org/bdware/sc/ContractManager.java b/src/main/java/org/bdware/sc/ContractManager.java
index 40dc459..3d6f51e 100644
--- a/src/main/java/org/bdware/sc/ContractManager.java
+++ b/src/main/java/org/bdware/sc/ContractManager.java
@@ -799,6 +799,11 @@ public class ContractManager {
         try {
             if (c.getScriptStr().startsWith("/")) {
                 c.startInfo.isYPK = true;
+                File ypkFile = new File(c.getScriptStr());
+                if (!ypkFile.exists()) {
+                    r = new ContractResult(Status.Error, new JsonPrimitive("no such ypk file"));
+                    return JsonUtil.toJson(r);
+                }
                 String[] str = c.getScriptStr().split("/");
                 String tmp = new File(dir + "/publicCompiled/ypkName").getAbsolutePath();
                 String[] str2 = tmp.split("/");
@@ -924,7 +929,7 @@ public class ContractManager {
             }
         } catch (Exception e) {
             e.printStackTrace();
-            r = new ContractResult(Status.Error, new JsonPrimitive("exception occurs"));
+            r = new ContractResult(Status.Error, new JsonPrimitive("exception occurs: " + e.getMessage()));
             return JsonUtil.toJson(r);
         }
     }
diff --git a/src/main/java/org/bdware/sc/MultiContractRecorder.java b/src/main/java/org/bdware/sc/MultiContractRecorder.java
index 601dbac..4cb3c27 100644
--- a/src/main/java/org/bdware/sc/MultiContractRecorder.java
+++ b/src/main/java/org/bdware/sc/MultiContractRecorder.java
@@ -23,7 +23,7 @@ public class MultiContractRecorder extends StatusRecorder<MultiContractMeta> {
                                         CMTables.LastExeSeq.toString(), meta.getContractID()));
                 meta.setLastExeSeq(lastExeSeq);
             } catch (Exception e) {
-                e.printStackTrace();
+                LOGGER.error(e);
             }
         }
     }