Why Am I Getting a 'java.net.ConnectException: Connection Refused' Error?

Connection Refused: Delving into the 'java.net.ConnectException' Quandary

When attempting to establish a TCP connection, encountering the "java.net.ConnectException: Connection refused" error can leave programmers perplexed. This exception signifies that no service is listening on the intended IP and port, hindering connection establishment.

Possible Culprits Behind the Connection Refusal:

• Misdirected Connection: Verify that you are connecting to the correct IP address or hostname and port number. Misconfigurations in this area can lead to connection failures.
• Non-Existent Server: Ensure that the server you are attempting to connect to is actually running and listening for incoming connections. If not, start the server and ensure its configuration allows for client connections.
• Firewall Interference: Check if any firewalls are active and configured to block incoming connections on the specified port. Adjust the firewall settings accordingly to allow for successful communication.
• Backlogged Queue (Windows Only): On Windows servers, the "listen backlog" queue can become full when too many connection requests are received simultaneously. This can lead to the "ConnectException," so it is important to adjust the server's configuration to handle a larger backlog or reduce connection attempts.

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