diff --git a/src/main/java/com/actiontech/dble/backend/datasource/PhysicalDbGroup.java b/src/main/java/com/actiontech/dble/backend/datasource/PhysicalDbGroup.java
index ea0156954d..24d0cd5510 100644
--- a/src/main/java/com/actiontech/dble/backend/datasource/PhysicalDbGroup.java
+++ b/src/main/java/com/actiontech/dble/backend/datasource/PhysicalDbGroup.java
@@ -330,7 +330,7 @@ public void startHeartbeat() {
 
     public void startDelayDetection() {
         for (PhysicalDbInstance dbInstance : allSourceMap.values()) {
-            if (dbInstance.delayDetection.isStop()) {
+            if (dbInstance.delayDetection != null && dbInstance.delayDetection.isStop()) {
                 dbInstance.delayDetection = new DelayDetection(dbInstance);
             }
             dbInstance.startDelayDetection();
diff --git a/src/main/java/com/actiontech/dble/singleton/ThreadManager.java b/src/main/java/com/actiontech/dble/singleton/ThreadManager.java
index 85af0d958f..2b47c6018e 100644
--- a/src/main/java/com/actiontech/dble/singleton/ThreadManager.java
+++ b/src/main/java/com/actiontech/dble/singleton/ThreadManager.java
@@ -115,7 +115,7 @@ public static void recoverSingleThread(String threadName) throws Exception {
                     }
                     break;
                 default:
-                    throw new Exception("The recover operation of threadPool[" + threadName + "] is not supported");
+                    throw new Exception("The recover operation of thread[" + threadName + "] is not supported");
             }
         } else {
             throw new Exception("The recover operation of thread[" + threadName + "] is not supported");