Request Reply deadlocking coming from WPF application

Description

Hello, I am currently attempting to use the NATS Request/Reply functionality from within a WPF app. The behavior I am currently seeing however, is that once my request goes into the NATSConnection, my application deadlocks until the timeout is completed. The subscriber never receives the message. Below is an example of the basic WPF I have spun up to recreate the issue, have tried both async and sync.

namespace TestWPFNats
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private async void Button_Click(object sender, RoutedEventArgs e)
        {
            var guid = Guid.NewGuid().ToString();
            var clientId = Guid.NewGuid().ToString();
            var configurationRetriever = new MessagingConfigurationRetriever();
            
            var natsConnectionOptions = NatsOptionsFactory.Create().Build(configurationRetriever.HostsAndPorts, clientId);
            var natsConnection = new ConnectionFactory().CreateConnection(natsConnectionOptions);
            
            var proto = new RandomProtoObject();
            
            var response = await natsConnection.RequestAsync("my_topic_name", proto.ToByteArray(), 60000);
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            var guid = Guid.NewGuid().ToString();
            var clientId = Guid.NewGuid().ToString();
            var configurationRetriever = new MessagingConfigurationRetriever();
            
            var natsConnectionOptions = NatsOptionsFactory.Create().Build(configurationRetriever.HostsAndPorts, clientId);
            var natsConnection = new ConnectionFactory().CreateConnection(natsConnectionOptions);
            
            var proto = new RandomProtoObject();
            
            var response = natsConnection.Request("my_topic_name", proto.ToByteArray(), 60000);
        }
    }
}

Any help would be greatly appreciated, not sure where else to look. I suspected at first it may have had to do with the InFlightResponse TaskCompletionSource, but unsure if thats the case, since the message is never even being sent out.

Versions

C# nats.net (0.12.0) nats-server (2.5.0) nats-c (2.4.0)

[jasper-d]

@kharkins-23 That looks like nobody is responding to your message. Your message (request) is published on subject safetysettings.upsert.click, awaiting a response on _INBOX.uHgt21IfmyJOZiwF3EyTv2.1. But apparently the server never receives a response message.

I think the missing ->> [MSG safetysettings.upsert.click ...] line after MSG_PAYLOAD indicates that there is no subscriber. Can you double check that Request/RequestAsync does not throw a NATSNoRespondersException?

[ColinSullivan1]

True, the async error handler is only for NATS related errors/exceptions today. I can see how the exception being swallowed could make it difficult to debug. I think that’d be a good addition, and will open an issue to track that. Thanks!