diff --git a/Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs b/Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs
index e3780c7..ca9c700 100644
--- a/Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs
+++ b/Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs
@@ -169,25 +169,6 @@ namespace MQTTnet.Client.Options
             return WithTls(new MqttClientOptionsBuilderTlsParameters { UseTls = true });
         }
 
-        [Obsolete("Use method _WithTls_ which accepts the _MqttClientOptionsBuilderTlsParameters_.")]
-        public MqttClientOptionsBuilder WithTls(
-            bool allowUntrustedCertificates = false,
-            bool ignoreCertificateChainErrors = false,
-            bool ignoreCertificateRevocationErrors = false,
-            params byte[][] certificates)
-        {
-            _tlsParameters = new MqttClientOptionsBuilderTlsParameters
-            {
-                UseTls = true,
-                AllowUntrustedCertificates = allowUntrustedCertificates,
-                IgnoreCertificateChainErrors = ignoreCertificateChainErrors,
-                IgnoreCertificateRevocationErrors = ignoreCertificateRevocationErrors,
-                Certificates = certificates?.ToList()
-            };
-
-            return this;
-        }
-
         public IMqttClientOptions Build()
         {
             if (_tcpOptions == null && _webSocketOptions == null)
diff --git a/Source/MQTTnet/Implementations/MqttTcpChannel.cs b/Source/MQTTnet/Implementations/MqttTcpChannel.cs
index e6b7deb..33d9f18 100644
--- a/Source/MQTTnet/Implementations/MqttTcpChannel.cs
+++ b/Source/MQTTnet/Implementations/MqttTcpChannel.cs
@@ -44,9 +44,6 @@ namespace MQTTnet.Implementations
             CreateStream(sslStream);
         }
 
-        [Obsolete("There is a new callback at the TLS options. This one will be deleted soon.")]
-        public static Func<X509Certificate, X509Chain, SslPolicyErrors, MqttClientTcpOptions, bool> CustomCertificateValidationCallback { get; set; }
-
         public string Endpoint => _socket?.RemoteEndPoint?.ToString();
 
         public bool IsSecureConnection { get; }
@@ -134,18 +131,11 @@ namespace MQTTnet.Implementations
 
         private bool InternalUserCertificateValidationCallback(object sender, X509Certificate x509Certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
         {
-            // Try the instance callback.
             if (_options.TlsOptions.CertificateValidationCallback != null)
             {
                 return _options.TlsOptions.CertificateValidationCallback(x509Certificate, chain, sslPolicyErrors, _clientOptions);
             }
 
-            // Try static callback.
-            if (CustomCertificateValidationCallback != null)
-            {
-                return CustomCertificateValidationCallback(x509Certificate, chain, sslPolicyErrors, _options);
-            }
-
             if (sslPolicyErrors == SslPolicyErrors.None)
             {
                 return true;
@@ -197,25 +187,6 @@ namespace MQTTnet.Implementations
                 _stream = new NetworkStream(_socket, true);
             }
         }
-
-        private static void Cleanup<T>(ref T item, Action<T> handler) where T : class
-        {
-            var temp = item;
-            item = null;
-            try
-            {
-                if (temp != null)
-                {
-                    handler(temp);
-                }
-            }
-            catch (ObjectDisposedException)
-            {
-            }
-            catch (NullReferenceException)
-            {
-            }
-        }
     }
 }
 #endif
diff --git a/Source/MQTTnet/Server/MqttClientConnection.cs b/Source/MQTTnet/Server/MqttClientConnection.cs
index 4b75ff8..05a10a5 100644
--- a/Source/MQTTnet/Server/MqttClientConnection.cs
+++ b/Source/MQTTnet/Server/MqttClientConnection.cs
@@ -138,7 +138,9 @@ namespace MQTTnet.Server
 
                 Session.WillMessage = _connectPacket.WillMessage;
 
-                Task.Run(() => SendPendingPacketsAsync(), _cancellationToken.Token);
+#pragma warning disable 4014
+                Task.Run(() => SendPendingPacketsAsync(_cancellationToken.Token), _cancellationToken.Token);
+#pragma warning restore 4014
 
                 // TODO: Change to single thread in SessionManager. Or use SessionManager and stats from KeepAliveMonitor.
                 _keepAliveMonitor.Start(_connectPacket.KeepAlivePeriod, _cancellationToken.Token);
@@ -372,22 +374,22 @@ namespace MQTTnet.Server
             //await Task.FromResult(0);
         }
 
-        private async Task SendPendingPacketsAsync()
+        private async Task SendPendingPacketsAsync(CancellationToken cancellationToken)
         {
             MqttPendingApplicationMessage queuedApplicationMessage = null;
             MqttPublishPacket publishPacket = null;
 
             try
             {
-                while (!_cancellationToken.IsCancellationRequested)
+                while (!cancellationToken.IsCancellationRequested)
                 {
-                    queuedApplicationMessage = await Session.ApplicationMessagesQueue.TakeAsync(_cancellationToken.Token).ConfigureAwait(false);
+                    queuedApplicationMessage = await Session.ApplicationMessagesQueue.TakeAsync(cancellationToken).ConfigureAwait(false);
                     if (queuedApplicationMessage == null)
                     {
                         return;
                     }
 
-                    if (_cancellationToken.IsCancellationRequested)
+                    if (cancellationToken.IsCancellationRequested)
                     {
                         return;
                     }