diff --git a/MQTTnet.Core/Server/MqttClientPendingMessagesQueue.cs b/MQTTnet.Core/Server/MqttClientPendingMessagesQueue.cs
index 551dc8e..f16f689 100644
--- a/MQTTnet.Core/Server/MqttClientPendingMessagesQueue.cs
+++ b/MQTTnet.Core/Server/MqttClientPendingMessagesQueue.cs
@@ -28,7 +28,7 @@ namespace MQTTnet.Core.Server
         {
             if (adapter == null) throw new ArgumentNullException(nameof(adapter));
 
-            Task.Run(() => SendPendingPublishPacketsAsync(adapter, cancellationToken), cancellationToken);
+            Task.Factory.StartNew(async () => await SendPendingPublishPacketsAsync(adapter, cancellationToken), cancellationToken, TaskCreationOptions.LongRunning, TaskScheduler.Default).ConfigureAwait(false);
         }
 
         public void Enqueue(MqttPublishPacket publishPacket)
@@ -74,7 +74,7 @@ namespace MQTTnet.Core.Server
                 {
                     _trace.Warning(nameof(MqttClientPendingMessagesQueue), exception, "Sending publish packet failed due to communication exception.");
                 }
-                if (exception is OperationCanceledException)
+                else if (exception is OperationCanceledException)
                 {
                 }
                 else
diff --git a/MQTTnet.Core/Server/MqttClientSession.cs b/MQTTnet.Core/Server/MqttClientSession.cs
index f913901..5941a4f 100644
--- a/MQTTnet.Core/Server/MqttClientSession.cs
+++ b/MQTTnet.Core/Server/MqttClientSession.cs
@@ -45,10 +45,9 @@ namespace MQTTnet.Core.Server
         {
             if (adapter == null) throw new ArgumentNullException(nameof(adapter));
 
-            _willMessage = willMessage;
-
             try
             {
+                _willMessage = willMessage;
                 _adapter = adapter;
                 _cancellationTokenSource = new CancellationTokenSource();
 
@@ -70,18 +69,23 @@ namespace MQTTnet.Core.Server
 
         public void Stop()
         {
-            if (_willMessage != null)
+            try
             {
-                _mqttClientSessionsManager.DispatchApplicationMessage(this, _willMessage);
-            }
-
-            _cancellationTokenSource?.Cancel(false);
-            _cancellationTokenSource?.Dispose();
-            _cancellationTokenSource = null;
+                _cancellationTokenSource?.Cancel(false);
+                _cancellationTokenSource?.Dispose();
+                _cancellationTokenSource = null;
 
-            _adapter = null;
+                _adapter = null;
 
-            _trace.Information(nameof(MqttClientSession), "Client '{0}': Disconnected.", ClientId);
+                _trace.Information(nameof(MqttClientSession), "Client '{0}': Disconnected.", ClientId);
+            }
+            finally
+            {
+                if (_willMessage != null)
+                {
+                    _mqttClientSessionsManager.DispatchApplicationMessage(this, _willMessage);
+                }
+            }
         }
 
         public void EnqueuePublishPacket(MqttPublishPacket publishPacket)
diff --git a/MQTTnet.Core/Server/MqttClientSessionsManager.cs b/MQTTnet.Core/Server/MqttClientSessionsManager.cs
index aedd3d7..6238f2c 100644
--- a/MQTTnet.Core/Server/MqttClientSessionsManager.cs
+++ b/MQTTnet.Core/Server/MqttClientSessionsManager.cs
@@ -160,6 +160,7 @@ namespace MQTTnet.Core.Server
                         _clientSessions.Remove(connectPacket.ClientId);
                         clientSession.Dispose();
                         clientSession = null;
+
                         _trace.Verbose(nameof(MqttClientSessionsManager), "Disposed existing session of client '{0}'.", connectPacket.ClientId);
                     }
                     else