how to solve this error: RabbitMQ.Client.Exceptions.BrokerUnreachableException: 'None of the specified endpoints were reachable'

Question

i'm working in eshop order basket project. i want help for solving rabbitmq error from this code:

using Microsoft.Extensions.Logging; 
using Polly; 
using Polly.Retry; 
using RabbitMQ.Client; 
using RabbitMQ.Client.Events; 
using RabbitMQ.Client.Exceptions; 
using System; 
using System.IO; 
using System.Net.Sockets; 

namespace InfiniteWorx.MRU.BuildingBlocks.EventBusRabbitMQ 
{ 
    public class DefaultRabbitMQPersistentConnection 
       : IRabbitMQPersistentConnection 
    { 
        private readonly IConnectionFactory _connectionFactory;  
        private readonly ILogger<DefaultRabbitMQPersistentConnection> _logger; 
        private readonly int _retryCount; 
        IConnection _connection; 
        bool _disposed; 
        object sync_root = new object(); 
        public DefaultRabbitMQPersistentConnection(IConnectionFactory 
connectionFactory, ILogger<DefaultRabbitMQPersistentConnection> logger, int 
retryCount = 5) 
        { 
            _connectionFactory = connectionFactory ?? throw new 
ArgumentNullException(nameof(connectionFactory)); 
            _logger = logger ?? throw new 
ArgumentNullException(nameof(logger)); 
            _retryCount = retryCount; 
        } 
        public bool IsConnected 
        { 
            get 
            { 
                return _connection != null && _connection.IsOpen && 
!_disposed; 
            } 
        } 
        public IModel CreateModel() 
        { 
            if (!IsConnected) 
            { 
                throw new InvalidOperationException("No RabbitMQ connections 
are available to perform this action"); 
            } 

            return _connection.CreateModel(); 
        } 

        public void Dispose() 
        { 
            if (_disposed) return; 

            _disposed = true; 

            try 
            { 
                _connection.Dispose(); 

            } 
            catch (IOException ex) 
            { 
                _logger.LogCritical(ex.ToString()); 
            } 
        } 

        public bool TryConnect() 
        { 
            _logger.LogInformation("RabbitMQ Client is trying to connect"); 

            lock (sync_root) 
            { 
                var policy = RetryPolicy.Handle<SocketException>() 
                    .Or<BrokerUnreachableException>() 
                    .WaitAndRetry(_retryCount, retryAttempt => 
TimeSpan.FromSeconds(Math.Pow(2, retryAttempt)), (ex, time) => 
                    { 
                        _logger.LogWarning(ex.ToString()); 
                    } 
                ); 

                policy.Execute(() => 
                { 
                    _connection = _connectionFactory 
                          .CreateConnection(); 
                }); 

                if (IsConnected) 
                { 
                    _connection.ConnectionShutdown += OnConnectionShutdown; 
                    _connection.CallbackException += OnCallbackException; 
                    _connection.ConnectionBlocked += OnConnectionBlocked; 

                    _logger.LogInformation($"RabbitMQ persistent connection 
acquired a connection {_connection.Endpoint.HostName} and is subscribed to 
failure events"); 

                    return true; 
                } 
                else 
                { 
                    _logger.LogCritical("FATAL ERROR: RabbitMQ connections 
could not be created and opened"); 

                    return false; 
                } 
            } 
        } 

        private void OnConnectionBlocked(object sender, 
ConnectionBlockedEventArgs e) 
        { 
            if (_disposed) return; 

            _logger.LogWarning("A RabbitMQ connection is shutdown. Trying to 
re-connect..."); 

            TryConnect(); 
        } 

        void OnCallbackException(object sender, CallbackExceptionEventArgs e) 
        { 
            if (_disposed) return; 

            _logger.LogWarning("A RabbitMQ connection throw exception. 
Trying to re-connect..."); 

            TryConnect(); 
        } 

        void OnConnectionShutdown(object sender, ShutdownEventArgs reason) 
        { 
            if (_disposed) return; 

            _logger.LogWarning("A RabbitMQ connection is on shutdown. Trying to re-connect..."); 

            TryConnect(); 
        } 
    } 
} 

This is eroor msg when running the code:

RabbitMQ.Client.Exceptions.BrokerUnreachableException: 'None of the specified endpoints were reachable'

ArgumentNullException: Value cannot be null. ConnectFailureException: Connection failed

Answer 1

I don't see you set your connection parameters anywhere.

Typically:

RabbitMQ.Client.Exceptions.BrokerUnreachableException: 'None of the specified endpoints were reachable

means that your connection parameters are incorrect, so please check them.

---

As by Aage's comment:

A password with special characters (like an @) can cause this exception as well.

---

From the RabbitMQsite:

ConnectionFactory factory = new ConnectionFactory();
// "guest"/"guest" by default, limited to localhost connections
factory.UserName = user;
factory.Password = pass;
factory.VirtualHost = vhost;
factory.HostName = hostName;

IConnection conn = factory.CreateConnection();

Or alternatively:

ConnectionFactory factory = new ConnectionFactory();
factory.Uri = "amqp://user:pass@hostName:port/vhost";

IConnection conn = factory.CreateConnection();

So, my guess is, that one of these parameters are incorrect for your setup. Please check them.

Please note:

guest account is only accessible from localhost.

If possible, you might want to check Masstransit, which adds an abstraction layer to the MQ.