What's causing my java.net.SocketException: Connection reset?

A java.net.SocketException: Connection reset can be caused by a variety of issues, such as:

• The remote host abruptly closed or reset the connection.
• A network interruption, firewall rule, or proxy configuration caused the connection to be reset.

Here are a few things you can try to troubleshoot this issue:

• Verify the remote host is up and reachable.
• Check for network interruptions, firewall rules, or proxy configurations that might drop connections.
• Review server and client logs for Connection reset by peer messages.
• Adjust the SO_TIMEOUT socket option. Note that SO_TIMEOUT only applies to blocking read() operations and will not prevent TCP connection resets, but it can help handle slow or unresponsive endpoints.

try (Socket socket = new Socket("example.com", 80)) {
    socket.setSoTimeout(5000); // 5 seconds for read operations
    // ... perform I/O
} catch (SocketException e) {
    if (e.getMessage() != null && e.getMessage().contains("Connection reset")) {
        // Handle reset (e.g., retry logic, logging)
    }
}

If these steps do not help, debug the code to find the root cause. You can use a packet capture tool like Wireshark to inspect network traffic. A useful filter for this scenario is tcp.flags.reset == 1 to isolate RST packets.

I hope this helps! Let me know if you have any questions.