when storage a received message raising an eception, we will reject the message to queue.

src/DotNetCore.CAP.Kafka/KafkaConsumerClient.cs

@@ -45,6 +45,7 @@ namespace DotNetCore.CAP.Kafka
                 cancellationToken.ThrowIfCancellationRequested();
                 _consumerClient.Poll(timeout);
             }
+            // ReSharper disable once FunctionNeverReturns
         }
 
         public void Commit()
@@ -52,6 +53,11 @@ namespace DotNetCore.CAP.Kafka
             _consumerClient.CommitAsync();
         }
 
+        public void Reject()
+        {
+            // Ignore, Kafka will not commit offset when not commit.
+        }
+
         public void Dispose()
         {
             _consumerClient.Dispose();
@@ -65,11 +71,16 @@ namespace DotNetCore.CAP.Kafka
 
             var config = _kafkaOptions.AsKafkaConfig();
             _consumerClient = new Consumer<Null, string>(config, null, StringDeserializer);
-
+            _consumerClient.OnConsumeError += ConsumerClient_OnConsumeError;
             _consumerClient.OnMessage += ConsumerClient_OnMessage;
             _consumerClient.OnError += ConsumerClient_OnError;
         }
 
+        private void ConsumerClient_OnConsumeError(object sender, Message e)
+        {
+            OnError?.Invoke(sender, $"Consumer client raised an error. Topic:{e.Topic}, Reason:{e.Error}");
+        }
+
         private void ConsumerClient_OnMessage(object sender, Message<Null, string> e)
         {
             var message = new MessageContext
@@ -84,7 +95,7 @@ namespace DotNetCore.CAP.Kafka
 
         private void ConsumerClient_OnError(object sender, Error e)
         {
-            OnError?.Invoke(sender, e.Reason);
+            OnError?.Invoke(sender, e.ToString());
         }
 
         #endregion private methods

src/DotNetCore.CAP.RabbitMQ/RabbitMQConsumerClient.cs

@@ -57,6 +57,11 @@ namespace DotNetCore.CAP.RabbitMQ
             _channel.BasicAck(_deliveryTag, false);
         }
 
+        public void Reject()
+        {
+            _channel.BasicReject(_deliveryTag, true);
+        }
+
         public void Dispose()
         {
             _channel.Dispose();
@@ -73,7 +78,7 @@ namespace DotNetCore.CAP.RabbitMQ
                 RabbitMQOptions.ExchangeType,
                 true);
 
-            var arguments = new Dictionary<string, object> {{"x-message-ttl", _rabbitMQOptions.QueueMessageExpires}};
+            var arguments = new Dictionary<string, object> { { "x-message-ttl", _rabbitMQOptions.QueueMessageExpires } };
             _channel.QueueDeclare(_queueName,
                 true,
                 false,

src/DotNetCore.CAP/IConsumerClient.cs

@@ -15,6 +15,8 @@ namespace DotNetCore.CAP
 
         void Commit();
 
+        void Reject();
+
         event EventHandler<MessageContext> OnMessageReceived;
 
         event EventHandler<string> OnError;

src/DotNetCore.CAP/IConsumerHandler.Default.cs

@@ -91,9 +91,16 @@ namespace DotNetCore.CAP
 
                 using (var scope = _serviceProvider.CreateScope())
                 {
-                    StoreMessage(scope, message);
-
-                    client.Commit();
+                    try
+                    {
+                        StoreMessage(scope, message);
+                        client.Commit();
+                    }
+                    catch (Exception e)
+                    {
+                        _logger.LogError(e, "Raised an exception when storage received message。 Message：{0}", message);
+                        client.Reject();
+                    }
                 }
                 Pulse();
             };