thingsboard-aplcache

diff --git a/netty-mqtt/src/main/java/org/thingsboard/mqtt/MqttClientImpl.java b/netty-mqtt/src/main/java/org/thingsboard/mqtt/MqttClientImpl.java
index b9460b3..2bfdeb6 100644
--- a/netty-mqtt/src/main/java/org/thingsboard/mqtt/MqttClientImpl.java
+++ b/netty-mqtt/src/main/java/org/thingsboard/mqtt/MqttClientImpl.java
@@ -390,7 +390,9 @@ final class MqttClientImpl implements MqttClient {
     }
 
     public void onSuccessfulReconnect() {
-        callback.onSuccessfulReconnect();
+        if (callback != null) {
+            callback.onSuccessfulReconnect();
+        }
     }