From 7d3959036ba790fb3556009667108e841016c434 Mon Sep 17 00:00:00 2001
From: nickAS21 <nick@thingsboard.io>
Date: Wed, 29 Jul 2026 13:36:34 +0300
Subject: [PATCH] sparkplug^ fix_bug close session after connect nodde

---
 .../mqtt/session/AbstractGatewaySessionHandler.java      | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/session/AbstractGatewaySessionHandler.java b/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/session/AbstractGatewaySessionHandler.java
index 8ea6480142..905814d06d 100644
--- a/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/session/AbstractGatewaySessionHandler.java
+++ b/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/session/AbstractGatewaySessionHandler.java
@@ -845,7 +845,14 @@ public abstract class AbstractGatewaySessionHandler<T extends AbstractGatewayDev
                     }
                 }
                 if (msgId <= 0) {
-                    closeDeviceSession(deviceName, MqttReasonCodes.Disconnect.MALFORMED_PACKET);
+                    if (deviceSessionCtx.isSparkplug()) {
+                        // Sparkplug devices may use msgId = 0 during the initial connection or for QoS 0 messages.
+                        // We bypass the MALFORMED_PACKET check to allow these sessions to proceed.
+                        log.trace("[{}] Sparkplug session: allowed msgId [{}] for device: [{}]", sessionId, msgId, deviceName);
+                    } else {
+                        // Standard MQTT defense: close session for invalid message IDs
+                        closeDeviceSession(deviceName, MqttReasonCodes.Disconnect.MALFORMED_PACKET);
+                    }
                 }
             }