diff --git a/OpenAuth.WebApi/Controllers/ServiceControllers/AirportMaintenanceController.cs b/OpenAuth.WebApi/Controllers/ServiceControllers/AirportMaintenanceController.cs
index 28e4df9..9d6f6a0 100644
--- a/OpenAuth.WebApi/Controllers/ServiceControllers/AirportMaintenanceController.cs
+++ b/OpenAuth.WebApi/Controllers/ServiceControllers/AirportMaintenanceController.cs
@@ -480,6 +480,8 @@ namespace OpenAuth.WebApi.Controllers.ServiceControllers
         }
         private MqttClientResp ParseClient(HashEntry[] entries)
         {
+            if (entries == null || entries.Length == 0)
+                return null;
             var dict = entries.ToDictionary(e => e.Name.ToString(), e => e.Value.ToString());
             return new MqttClientResp
             {
diff --git a/OpenAuth.WebApi/Startup.cs b/OpenAuth.WebApi/Startup.cs
index 8a0cd2c..1794e0b 100644
--- a/OpenAuth.WebApi/Startup.cs
+++ b/OpenAuth.WebApi/Startup.cs
@@ -329,10 +329,10 @@ namespace OpenAuth.WebApi
 
             #region mqtt
             services.AddSingleton<MqttMessageCenter>();
-            //services.AddSingleton<IMqttMessageHandler, ThingRequestHandler>();
-            //services.AddSingleton<IMqttMessageHandler, ThingServiceHandler>();
-            //services.AddSingleton<IMqttMessageHandler, ThingOsdHandler>();
-            //services.AddSingleton<IMqttMessageHandler, ThingEventHandler>();
+            services.AddSingleton<IMqttMessageHandler, ThingRequestHandler>();
+            services.AddSingleton<IMqttMessageHandler, ThingServiceHandler>();
+            services.AddSingleton<IMqttMessageHandler, ThingOsdHandler>();
+            services.AddSingleton<IMqttMessageHandler, ThingEventHandler>();
             services.AddSingleton<IMqttMessageHandler, ThingDrcHandler>();
             services.AddHostedService<MqttHostedService>();