diff --git a/application/src/test/java/org/thingsboard/server/transport/mqtt/mqttv3/credentials/BasicMqttCredentialsTest.java b/application/src/test/java/org/thingsboard/server/transport/mqtt/mqttv3/credentials/BasicMqttCredentialsTest.java
index 288d0ca45c..496a13ad70 100644
--- a/application/src/test/java/org/thingsboard/server/transport/mqtt/mqttv3/credentials/BasicMqttCredentialsTest.java
+++ b/application/src/test/java/org/thingsboard/server/transport/mqtt/mqttv3/credentials/BasicMqttCredentialsTest.java
@@ -16,7 +16,8 @@
 package org.thingsboard.server.transport.mqtt.mqttv3.credentials;
 
 import com.fasterxml.jackson.core.type.TypeReference;
-import org.eclipse.paho.client.mqttv3.MqttSecurityException;
+import org.eclipse.paho.client.mqttv3.MqttException;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.thingsboard.common.util.JacksonUtil;
@@ -114,11 +115,15 @@ public class BasicMqttCredentialsTest extends AbstractMqttIntegrationTest {
         testTelemetryIsDelivered(accessToken2Device, mqttTestClient5);
     }
 
-    @Test(expected = MqttSecurityException.class)
+    @Test
     public void testCorrectClientIdAndUserNameButWrongPassword() throws Exception {
         // Not correct. Correct clientId and username, but wrong password
         MqttTestClient mqttTestClient = new MqttTestClient(CLIENT_ID);
-        mqttTestClient.connectAndWait(USER_NAME3, "WRONG PASSWORD");
+        try {
+            mqttTestClient.connectAndWait(USER_NAME3, "WRONG PASSWORD");
+        } catch (MqttException e) {
+            Assert.assertEquals(4, e.getReasonCode()); // 4 - Reason code for bad username or password in MQTT v3
+        }
         testTelemetryIsNotDelivered(clientIdAndUserNameAndPasswordDevice3, mqttTestClient);
     }
 
diff --git a/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/MqttTransportHandler.java b/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/MqttTransportHandler.java
index c03a7dd441..2c3ac45326 100644
--- a/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/MqttTransportHandler.java
+++ b/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/MqttTransportHandler.java
@@ -1010,17 +1010,19 @@ public class MqttTransportHandler extends ChannelInboundHandlerAdapter implement
     private void onValidateDeviceResponse(ValidateDeviceCredentialsResponse msg, ChannelHandlerContext ctx, MqttConnectMessage connectMessage) {
         if (!msg.hasDeviceInfo()) {
             context.onAuthFailure(address);
-            if (MqttVersion.MQTT_5.equals(deviceSessionCtx.getMqttVersion())) {
-                ReturnCode returnCode = ReturnCode.NOT_AUTHORIZED_5;
-                if (sslHandler == null || getX509Certificate() == null) {
-                    if (connectMessage.payload().userName() == null ^ connectMessage.payload().passwordInBytes() == null) {
-                        returnCode = ReturnCode.BAD_USERNAME_OR_PASSWORD;
-                    } else if (!StringUtils.isBlank(connectMessage.payload().clientIdentifier())) {
-                        returnCode = ReturnCode.CLIENT_IDENTIFIER_NOT_VALID;
-                    }
+            ReturnCode returnCode = ReturnCode.NOT_AUTHORIZED_5;
+            if (sslHandler == null || getX509Certificate() == null) {
+                String username = connectMessage.payload().userName();
+                byte[] passwordBytes = connectMessage.payload().passwordInBytes();
+                String clientId = connectMessage.payload().clientIdentifier();
+                if ((username != null && passwordBytes != null && clientId != null)
+                        || (username == null ^ passwordBytes == null)) {
+                    returnCode = ReturnCode.BAD_USERNAME_OR_PASSWORD;
+                } else if (!StringUtils.isBlank(clientId)) {
+                    returnCode = ReturnCode.CLIENT_IDENTIFIER_NOT_VALID;
                 }
-                ctx.writeAndFlush(createMqttConnAckMsg(returnCode, connectMessage));
             }
+            ctx.writeAndFlush(createMqttConnAckMsg(returnCode, connectMessage));
             ctx.close();
         } else {
             context.onAuthSuccess(address);