Help Center> Distributed Message Service for RabbitMQ> User Guide (ME-Abu Dhabi Region)> FAQs> Connections> Why Does a Client Fail to Connect to a RabbitMQ Instance?
Updated on 2023-05-06 GMT+08:00
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Why Does a Client Fail to Connect to a RabbitMQ Instance?

This problem occurs when the connection address, port number, username, or password is incorrect, or when the maximum allowed number of connections is exceeded.

  • Incorrect connection address

    Error message displayed for an incorrect connection address in intra-VPC access:

    [root@ecs-heru RabbitMQ-Tutorial]# java -cp .:rabbitmq-tutorial.jar Send 192.168.125.110 5672 user *******
Exception in thread "main" java.net.NoRouteToHostException: No route to host (Host unreachable)
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)

    Error message displayed for an incorrect connection address in public access:

    [root@ecs-heru RabbitMQ-Tutorial]# java -cp .:rabbitmq-tutorial.jar Send 139.xxx.178 5672 user *******
Exception in thread "main" java.net.SocketTimeoutException: connect timed out
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
  • Incorrect port number

    Error message displayed for an incorrect port number in intra-VPC access:

    [root@ecs-heru RabbitMQ-Tutorial]# java -cp .:rabbitmq-tutorial.jar Send 192.168.125.111 5673 user *******
Exception in thread "main" java.net.ConnectException: Connection refused (Connection refused)
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)

    Error message displayed for an incorrect port number in public access:

    [root@ecs-heru RabbitMQ-Tutorial]# java -cp .:rabbitmq-tutorial.jar Send 139.xxx.179 5673 user *******
Exception in thread "main" java.net.SocketTimeoutException: connect timed out
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
  • Incorrect username or password
    [root@ecs-heru RabbitMQ-Tutorial]# java -cp .:rabbitmq-tutorial.jar Send 192.168.125.111 5672 user *******
Exception in thread "main" com.rabbitmq.client.AuthenticationFailureException: ACCESS_REFUSED - Login was refused using authentication mechanism PLAIN. For details
 see the broker logfile.
at com.rabbitmq.client.impl.AMQConnection.start(AMQConnection.java:351)
at com.rabbitmq.client.impl.recovery.RecoveryAwareAMQConnectionFactory.newConnection(RecoveryAwareAMQConnectionFactory.java:64)
  • Maximum number of connections exceeded
Parent topic: Connections