diff --git a/DBNMQTTool/main.py b/DBNMQTTool/main.py
index 3940b78..b6fd6ed 100644
--- a/DBNMQTTool/main.py
+++ b/DBNMQTTool/main.py
@@ -453,6 +453,8 @@ class MainWindow(QMainWindow):
             self._log(f"[模拟] → {topic}")
         except json.JSONDecodeError as e:
             QMessageBox.warning(self, "JSON 错误", str(e))
+        except Exception as e:
+            QMessageBox.critical(self, "发布失败", f"{type(e).__name__}: {e}")
 
     def _sim_send_loop(self):
         sn = self._sim_sn.text()
@@ -576,15 +578,18 @@ class MainWindow(QMainWindow):
         if not topic or not self._mqtt.connected:
             QMessageBox.warning(self, "提示", "请输入 Topic 并连接 Broker")
             return
+        raw = self._proto_payload.toPlainText().strip()
         try:
-            if self._proto_payload.toPlainText().strip():
-                payload = json.loads(self._proto_payload.toPlainText())
+            if raw:
+                payload = json.loads(raw)
             else:
                 payload = build_request(CMD_DEV_INFO_QUERY)
             self._mqtt.publish(topic, payload)
             self._log(f"[协议] → {topic}")
         except json.JSONDecodeError as e:
             QMessageBox.warning(self, "JSON 错误", str(e))
+        except Exception as e:
+            QMessageBox.critical(self, "发布失败", f"{type(e).__name__}: {e}")
 
     # ================================================================
     # 自定义 Topic 订阅/发布
@@ -677,48 +682,61 @@ class MainWindow(QMainWindow):
         topic = self._custom_pub_topic.text()
         if not topic:
             return
+        raw = self._custom_payload.toPlainText().strip()
         try:
-            payload = json.loads(self._custom_payload.toPlainText()) if self._custom_payload.toPlainText().strip() else {}
+            payload = json.loads(raw) if raw else {}
             qos = int(self._custom_qos.currentText())
             self._mqtt.publish(topic, payload, qos=qos)
             self._log(f"[自定义] → {topic}")
         except json.JSONDecodeError as e:
             QMessageBox.warning(self, "JSON 错误", str(e))
+        except Exception as e:
+            QMessageBox.critical(self, "发布失败", f"{type(e).__name__}: {e}")
+            self._log(f"[自定义] 发布失败: {e}")
 
     def _custom_subscribe(self):
-        if not self._mqtt.connected:
+        if not self._mqtt.connected or not self._mqtt._client:
             QMessageBox.warning(self, "提示", "请先连接 Broker")
             return
         topic = self._custom_sub_topic.text()
         if not topic:
             return
-        qos = int(self._custom_sub_qos.currentText())
-        self._mqtt._client.subscribe(topic, qos=qos)
-        self._custom_subs[topic] = qos
-        # 更新列表
-        found = False
-        for i in range(self._custom_sub_list.topLevelItemCount()):
-            item = self._custom_sub_list.topLevelItem(i)
-            if item.text(0) == topic:
-                item.setText(1, str(qos))
-                found = True
-                break
-        if not found:
-            self._custom_sub_list.addTopLevelItem(QTreeWidgetItem([topic, str(qos)]))
-        self._log(f"[订阅] {topic} (QoS={qos})")
+        try:
+            qos = int(self._custom_sub_qos.currentText())
+            self._mqtt._client.subscribe(topic, qos=qos)
+            self._custom_subs[topic] = qos
+            # 更新列表
+            found = False
+            for i in range(self._custom_sub_list.topLevelItemCount()):
+                item = self._custom_sub_list.topLevelItem(i)
+                if item.text(0) == topic:
+                    item.setText(1, str(qos))
+                    found = True
+                    break
+            if not found:
+                self._custom_sub_list.addTopLevelItem(QTreeWidgetItem([topic, str(qos)]))
+            self._log(f"[订阅] {topic} (QoS={qos})")
+        except Exception as e:
+            QMessageBox.critical(self, "订阅失败", f"{type(e).__name__}: {e}")
+            self._log(f"[订阅] 失败: {e}")
 
     def _custom_unsubscribe(self):
         items = self._custom_sub_list.selectedItems()
         if not items:
             return
+        if not self._mqtt._client:
+            return
         for item in items:
             topic = item.text(0)
-            if topic in self._custom_subs:
-                self._mqtt._client.unsubscribe(topic)
-                del self._custom_subs[topic]
-            idx = self._custom_sub_list.indexOfTopLevelItem(item)
-            self._custom_sub_list.takeTopLevelItem(idx)
-            self._log(f"[取消订阅] {topic}")
+            try:
+                if topic in self._custom_subs:
+                    self._mqtt._client.unsubscribe(topic)
+                    del self._custom_subs[topic]
+                idx = self._custom_sub_list.indexOfTopLevelItem(item)
+                self._custom_sub_list.takeTopLevelItem(idx)
+                self._log(f"[取消订阅] {topic}")
+            except Exception as e:
+                self._log(f"[取消订阅] 失败: {e}")
 
     # ================================================================
     # MQTT