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

java

network-packets

http-client-logging

tls-compatibility

byNikita Barsukov·Mar 12, 2025

The error java.net.SocketException: Connection reset indicates a sudden disconnection, possibly due to TCP packets being unacknowledged by both sides. Ensure your network code handles resources and exceptions correctly.

Key Tactics:

Server-side logs: These clues can help figure out what's wrong.
Try-catch blocks: Specifically for capturing IOExceptions.
Resource cleanup: Do this in a finally block to avoid resource leaks.

try {
    // Place your network logic here and pray to the semicolon Gods...
} catch (IOException e) {
    // Let's handle this exception with dignity... also, a log might help!
} finally {
    // Clean up after the party
    closeQuietly(outputStream);
    closeQuietly(inputStream);
    closeQuietly(socket);
}

private void closeQuietly(AutoCloseable resource) {
    // Check if it's not a null party!
    if (resource != null) {
        try {
            resource.close();
        } catch (Exception ignored) {
            // Swallowing an exception? Don't tell mom!
        }
    }
}

Unraveling the Mystery: Diagnostic Tools

Your Connection reset error is a networking whodunit—it's time to play detective!

Network Traffic Analysis

Wireshark: Snoop on network packets—did the server hang up or was it the network?
Alternate Clients: Another debug tool—test the web service using different clients.
HTTP Client Logging: Eavesdrop on the HTTP dialog—with Commons HTTP Client Logging see request and response details.

Comprehending Server Configs

Max HTTP Header Size: Extensive or elaborate requests? Scale up the header size.
Thread Pool Settings: Your app is parallelizing—configure http-thread-pool to handle concurrent threads effectively.

Decrypting SSL and TLS

TLS Compatibility: Check if your client and server handshake properly—ensure Java supports the required TLS version.
SSL Libraries: Can't resolve the issue? Swap your SSL library!