RabbitMq connection failed exception on production server

Question

I have a windows forms application that is built on .NET 4.6.2. I'm connecting the app to rabbitmq using below code. Rabbit mq services are deployed on a separate server.

var factory = new ConnectionFactory() { HostName = _host, Port = _port, UserName = _userName, Password = _password };
if (_port != 5672){
factory.Ssl.Enabled = true;
factory.Ssl.Version = System.Security.Authentication.SslProtocols.Tls12;
factory.Ssl.CertificateValidationCallback = delegate (object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) { return true; };}
Client = factory.CreateConnection();
Channel = Client.CreateModel();

This is working completely fine in production. Now recently we were planning a new release where there were changes in other components but no changes in this app however when I run the app on production server it gives below exception.

RabbitMQ.Client.Exceptions.BrokerUnreachableException: None of the specified endpoints were reachable ---> System.IO.IOException: connection.start was never received, likely due to a network timeout
   at RabbitMQ.Client.Framing.Impl.Connection.StartAndTune()
   at RabbitMQ.Client.Framing.Impl.Connection.Open(Boolean insist)
   at RabbitMQ.Client.Framing.Impl.AutorecoveringConnection.Init(IFrameHandler fh)
   at RabbitMQ.Client.ConnectionFactory.CreateConnection(IEndpointResolver endpointResolver, String clientProvidedName)
   --- End of inner exception stack trace ---
   at RabbitMQ.Client.ConnectionFactory.CreateConnection(IEndpointResolver endpointResolver, String clientProvidedName)
   at LiveStatisticsBroker.CheckAndUpdateSessionStatus() in LiveStatistics.cs:line 105

There are no changes in the code and if I revert to the previous release it works fine. I have checked network connectivity and there are no issues even if I telnet the server IP and with port 5671 it gets succeeded.

Strange thing is If I place same release on development server rabbitmq gets connected. Our development servers also follow same network rules. I have been stuck on this for some time and couldn't get any success.

Answer 1

Upgrading RabbitMq.Client nuget package from 6.2.1 to 6.5.0 did the trick for me. System.Memory was also upgraded as a dependency.