EC
SocketException
JavaERRORNotableNetwork

Socket operation failed — connection broken or refused

Quick Answer

Set SO_TIMEOUT to prevent hanging indefinitely, and implement retry with exponential back-off.

What this means

Thrown when a socket operation fails — connection reset by peer, refused, or socket closed while blocking.

Why it happens
  1. 1Remote server closed connection mid-transfer
  2. 2Firewall silently dropped the TCP connection

Fix

Set socket timeout

Set socket timeout
Socket s = new Socket();
s.setSoTimeout(5000);
s.connect(new InetSocketAddress(host, port), 3000);

Why this works

SO_TIMEOUT throws SocketTimeoutException on blocked reads instead of hanging forever.

Code examples
Catch connection resetjava
try {
    in.read(buf);
} catch (SocketException e) {
    log.warn("Connection reset: {}", e.getMessage());
}
HttpClient timeoutjava
HttpClient client = HttpClient.newBuilder()
    .connectTimeout(Duration.ofSeconds(5))
    .build();
Retry with back-offjava
int delay = 500;
for (int i = 0; i < 3; i++, delay *= 2) {
    try { return call(); }
    catch (SocketException e) { Thread.sleep(delay); }
}
Sources
Official documentation ↗

Java SE Documentation

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