Cannot publish event in NServiceBus - Message type could not be determined by a 'Type.GetType', scanning known messages for a match

Question

I ran into a strange issue with publishing events to MSMQ using NServiceBus. I can successfully send messages using IBus.Send method (I can find the sent messages in MSMQ). However, when I try to publish an event using IBus.Publish method, the messages do not reach MSMQ. For each published message I only get the following log message.

[DEBUG] 2015-11-20 13:19:43.9444 Message type: 'MyAssembly.Messages.NewEmailEvent' could not be determined by a 'Type.GetType', scanning known messages for a match

The event definition looks like this.

namespace MyAssembly.Messages
{
    public class NewEmailEvent
    {
        public Guid MessageId { get; set; }
        public string Subject { get; set; }
        public string Sender { get; set; }
        // a few other fields
    }
}

I am publishing the event using the following code.

m_Bus.Publish<NewEmailEvent>(msg => {
    msg.MessageId = entry.MessageId;
    msg.Subject = entry.Email.Subject;
    msg.Sender = entry.Email.Sender.Name;
    // more property assignments
});

I have the following routing configuration.

<MsmqTransportConfig InputQueue="Nsb_input" ErrorQueue="Nsb_errors" NumberOfWorkerThreads="1" MaxRetries="5" />
<MessageForwardingInCaseOfFaultConfig ErrorQueue="error" />
<UnicastBusConfig>
  <MessageEndpointMappings>
    <add Assembly="MyAssembly.Messages" Endpoint="NServiceBus.Service" />
  </MessageEndpointMappings>
</UnicastBusConfig>

The event naming conventions are defined in code as follows.

busConfiguration.Conventions().DefiningEventsAs(
    t => t.Assembly.GetName().Name.EndsWith(".Messages", StringComparison.InvariantCulture)
        && t.Name.EndsWith("Event", StringComparison.InvariantCulture));

The messages are correctly registered at startup.

[DEBUG] 2015-11-20 13:18:35.1345 Message definitions: 
MessageType: MyAssembly.Messages.NewEmailEvent, Recoverable: True, TimeToBeReceived: Not set , Parent types: MyAssembly.Messages.NewEmailEvent
MessageType: NServiceBus.Scheduling.Messages.ScheduledTask, Recoverable: True, TimeToBeReceived: Not set , Parent types: NServiceBus.Scheduling.Messages.ScheduledTask

On the receiving end, I am subscribing to the event using the following code.

bus.Subscribe<NewEmailEvent>();

And using the following configuration.

<UnicastBusConfig>
  <MessageEndpointMappings>
    <add Assembly="MyAssembly.Messages" Endpoint="NServiceBus.Service" />
  </MessageEndpointMappings>
</UnicastBusConfig>
<MessageForwardingInCaseOfFaultConfig ErrorQueue="error" />

The event naming conventions are the same as the service.

I updated my question with the source code and configuration of the subscribing application. — Marek Dzikiewicz
And what is at the "NServiceBus.Service" endpoint? Shooting from the hip, I'd say you need to change your MessageEndpointMappings at the subscriber side to point to Nsb_input instead. — Udi Dahan
Did you resolve your issue? Is the message convention applied on both the publisher and the subscriber and are they identical? — Ramon Smits
"NServiceBus.Service" is the endpoint of the application which sends the events (the endpoint name is set using BusConfiguration.EndpointName). After changing MessageEndpointMappings at the subscriber side to Nsb_input, I get an error that the queue does not exist. And in fact it does not exist. On the other hand the nservicebus.service queue exists (NServiceBus created it at startup). — Marek Dzikiewicz

Justin Justin · Accepted Answer · 2015-12-06T19:35:53

Your MessageEndpointMappings are the same for both publisher and subscriber - don't know if this is correct / makes a difference.

You have not defined any message or command conventions; only events.

busConfiguration.Conventions()
    .DefiningMessagesAs(t => t.Namespace != null &&
                         t.Namespace.StartsWith("MyAssembly.Messages"))
    .DefiningCommandsAs(t => t.Namespace != null &&
                         t.Namespace.StartsWith("MyAssembly.Commands"))

I think you need to do this if you're not using marker interfaces.

I think this is especially important within the subscriber.

You haven't included the code for your subscriber. Does it have a class that implements IHandleMessages<NewEmailEvent>?

Go back and look at the pub/sub example.

Check your config settings again. It doesn't look like you're using external files; the sections are directly in app.config

Cannot publish event in NServiceBus - Message type could not be determined by a 'Type.GetType', scanning known messages for a match

1 Answers