No longer throw exception when receiving non success CONNACK

Source/MQTTnet.Tests/Clients/MqttClient/MqttClient_Connection_Tests.cs

@@ -220,7 +220,7 @@ public async Task Return_Non_Success()
 
                 var client = testEnvironment.CreateClient();
 
-                var response = await client.ConnectAsync(testEnvironment.CreateDefaultClientOptionsBuilder().WithoutThrowOnNonSuccessfulConnectResponse().Build());
+                var response = await client.ConnectAsync(testEnvironment.CreateDefaultClientOptionsBuilder().Build());
 
                 Assert.IsNotNull(response);
                 Assert.AreEqual(MqttClientConnectResultCode.QuotaExceeded, response.ResultCode);

Source/MQTTnet.Tests/Server/General.cs

@@ -102,8 +102,10 @@ public async Task Deny_Connection()
                     return CompletedTask.Instance;
                 };
 
-                var connectingFailedException = await Assert.ThrowsExceptionAsync<MqttConnectingFailedException>(() => testEnvironment.ConnectClient());
-                Assert.AreEqual(MqttClientConnectResultCode.NotAuthorized, connectingFailedException.ResultCode);
+                var client = testEnvironment.CreateClient();
+                var response = await client.ConnectAsync(testEnvironment.CreateDefaultClientOptions());
+
+                Assert.AreEqual(MqttClientConnectResultCode.NotAuthorized, response.ResultCode);
             }
         }
 

Source/MQTTnet.Tests/Server/Security_Tests.cs

@@ -22,7 +22,7 @@ public async Task Do_Not_Affect_Authorized_Clients()
             using (var testEnvironment = CreateTestEnvironment())
             {
                 testEnvironment.IgnoreClientLogErrors = true;
-                
+
                 await testEnvironment.StartServer();
 
                 var publishedApplicationMessages = new List<MqttApplicationMessage>();
@@ -81,15 +81,15 @@ await invalidClient.ConnectAsync(
                     }
 
                     await LongTestDelay();
-                    
+
                     await validClient.PublishStringAsync("HELLO 2");
-                    
+
                     await LongTestDelay();
-                    
+
                     await validClient.PublishStringAsync("HELLO 3");
-                    
+
                     await LongTestDelay();
-                    
+
                     Assert.AreEqual(3, publishedApplicationMessages.Count);
                     Assert.AreEqual(1, testEnvironment.Server.GetClientsAsync().GetAwaiter().GetResult().Count);
                 }
@@ -133,7 +133,6 @@ public async Task Use_Username_Null_Password_Empty()
                 var ex = await Assert.ThrowsExceptionAsync<MqttConnectingFailedException>(async () => await client.ConnectAsync(clientOptions));
                 Assert.IsInstanceOfType(ex.InnerException, typeof(MqttProtocolViolationException));
                 Assert.AreEqual("Error while authenticating. If the User Name Flag is set to 0, the Password Flag MUST be set to 0 [MQTT-3.1.2-22].", ex.Message, false);
-                Assert.AreEqual(MqttClientConnectResultCode.UnspecifiedError, ex.ResultCode);
             }
         }
 
@@ -164,8 +163,8 @@ async Task TestCredentials(string userName, string password)
 
                 var clientOptions = new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort).WithCredentials(userName, password).Build();
 
-                var ex = await Assert.ThrowsExceptionAsync<MqttConnectingFailedException>(() => client.ConnectAsync(clientOptions));
-                Assert.AreEqual(MqttClientConnectResultCode.BadUserNameOrPassword, ex.Result.ResultCode);
+                var response = await client.ConnectAsync(clientOptions);
+                Assert.AreEqual(MqttClientConnectResultCode.BadUserNameOrPassword, response.ResultCode);
             }
         }
     }

Source/MQTTnet.Tests/Server/Server_Reference_Tests.cs

@@ -4,51 +4,39 @@
 
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Adapter;
 using MQTTnet.Client;
 using MQTTnet.Formatter;
-using MQTTnet.Implementations;
 using MQTTnet.Internal;
 using MQTTnet.Protocol;
 
-namespace MQTTnet.Tests.Server
+namespace MQTTnet.Tests.Server;
+
+[TestClass]
+public sealed class Server_Reference_Tests : BaseTestClass
 {
-    [TestClass]
-    public sealed class Server_Reference_Tests : BaseTestClass
+    [TestMethod]
+    public async Task Server_Reports_With_Reference_Server()
     {
-        [TestMethod]
-        public async Task Server_Reports_With_Reference_Server()
+        using (var testEnvironment = CreateTestEnvironment())
         {
-            using (var testEnvironment = CreateTestEnvironment())
+            testEnvironment.IgnoreClientLogErrors = true;
+
+            var server = await testEnvironment.StartServer();
+
+            server.ValidatingConnectionAsync += e =>
             {
-                testEnvironment.IgnoreClientLogErrors = true;
-
-                var server = await testEnvironment.StartServer();
-
-                server.ValidatingConnectionAsync += e =>
-                {
-                    e.ReasonCode = MqttConnectReasonCode.ServerMoved;
-                    e.ServerReference = "new_server";
-                    return CompletedTask.Instance;
-                };
-
-                try
-                {
-                    var client = testEnvironment.CreateClient();
-
-                    await client.ConnectAsync(new MqttClientOptionsBuilder()
-                        .WithProtocolVersion(MqttProtocolVersion.V500)
-                        .WithTcpServer("127.0.0.1", testEnvironment.ServerPort)
-                        .Build());
-
-                    Assert.Fail();
-                }
-                catch (MqttConnectingFailedException e)
-                {
-                    Assert.AreEqual(MqttClientConnectResultCode.ServerMoved, e.ResultCode);
-                    Assert.AreEqual("new_server", e.Result.ServerReference);
-                }
-            }
+                e.ReasonCode = MqttConnectReasonCode.ServerMoved;
+                e.ServerReference = "new_server";
+                return CompletedTask.Instance;
+            };
+
+            var client = testEnvironment.CreateClient();
+
+            var response = await client.ConnectAsync(
+                new MqttClientOptionsBuilder().WithProtocolVersion(MqttProtocolVersion.V500).WithTcpServer("127.0.0.1", testEnvironment.ServerPort).Build());
+
+            Assert.AreEqual(MqttClientConnectResultCode.ServerMoved, response.ResultCode);
+            Assert.AreEqual("new_server", response.ServerReference);
         }
     }
 }

Source/MQTTnet/Adapter/MqttConnectingFailedException.cs

@@ -3,19 +3,13 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
-using MQTTnet.Client;
 using MQTTnet.Exceptions;
 
 namespace MQTTnet.Adapter;
 
 public sealed class MqttConnectingFailedException : MqttCommunicationException
 {
-    public MqttConnectingFailedException(string message, Exception innerException, MqttClientConnectResult connectResult) : base(message, innerException)
+    public MqttConnectingFailedException(string message, Exception innerException) : base(message, innerException)
     {
-        Result = connectResult;
     }
-
-    public MqttClientConnectResult Result { get; }
-
-    public MqttClientConnectResultCode ResultCode => Result?.ResultCode ?? MqttClientConnectResultCode.UnspecifiedError;
 }

Source/MQTTnet/Client/MqttClient.cs

@@ -171,11 +171,6 @@ public async Task<MqttClientConnectResult> ConnectAsync(MqttClientOptions option
         }
         catch (Exception exception)
         {
-            if (exception is MqttConnectingFailedException connectingFailedException)
-            {
-                connectResult = connectingFailedException.Result;
-            }
-
             _disconnectReason = (int)MqttClientDisconnectOptionsReason.UnspecifiedError;
 
             _logger.Error(exception, "Error while connecting with server");
@@ -479,20 +474,7 @@ async Task<MqttClientConnectResult> Authenticate(IMqttChannelAdapter channelAdap
         }
         catch (Exception exception)
         {
-            throw new MqttConnectingFailedException($"Error while authenticating. {exception.Message}", exception, null);
-        }
-
-        // This is no feature. It is basically a backward compatibility option and should be removed in the future.
-        // The client should not throw any exception if the transport layer connection was successful and the server
-        // did send a proper ACK packet with a non success response.
-        if (options.ThrowOnNonSuccessfulConnectResponse)
-        {
-            if (result.ResultCode != MqttClientConnectResultCode.Success)
-            {
-                _logger.Warning(
-                    "Client will now throw an _MqttConnectingFailedException_. This is obsolete and will be removed in the future. Consider setting _ThrowOnNonSuccessfulResponseFromServer=False_ in client options.");
-                throw new MqttConnectingFailedException($"Connecting with MQTT server failed ({result.ResultCode}).", null, result);
-            }
+            throw new MqttConnectingFailedException($"Error while authenticating. {exception.Message}", exception);
         }
 
         _logger.Verbose("Authenticated MQTT connection with server established.");

Source/MQTTnet/Client/Options/MqttClientOptions.cs

@@ -104,11 +104,6 @@ public sealed class MqttClientOptions
     /// </summary>
     public uint SessionExpiryInterval { get; set; }
 
-    /// <summary>
-    ///     Gets or sets whether an exception should be thrown when the server has sent a non success ACK packet.
-    /// </summary>
-    public bool ThrowOnNonSuccessfulConnectResponse { get; set; } = true;
-
     /// <summary>
     ///     Gets or sets the timeout which will be applied at socket level and internal operations.
     ///     The default value is the same as for sockets in .NET in general.

Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs

@@ -230,16 +230,6 @@ public MqttClientOptionsBuilder WithoutPacketFragmentation()
         return this;
     }
 
-    /// <summary>
-    ///     The client will not throw an exception when the MQTT server responds with a non success ACK packet.
-    ///     This will become the default behavior in future versions of the library.
-    /// </summary>
-    public MqttClientOptionsBuilder WithoutThrowOnNonSuccessfulConnectResponse()
-    {
-        _options.ThrowOnNonSuccessfulConnectResponse = false;
-        return this;
-    }
-
     public MqttClientOptionsBuilder WithProtocolType(ProtocolType protocolType)
     {
         _tcpOptions.ProtocolType = protocolType;