I am developing a Java application that communicates with a third-party REST API. Frequently, the connection drops and I receive the java.net.SocketException: Connection reset error. This happens randomly during the data transfer phase. Is this caused by a timeout on my side, or is the server forcibly closing the connection? I'm using the standard HttpURLConnection class and I want to know how to handle this gracefully without crashing the app.
3 answers
A "Connection reset" typically means that the remote host has sent a TCP RST (reset) packet. This often happens if the server's process crashes, the server times out the connection due to inactivity, or you try to send data to a socket that the server has already closed. In Java, this error is common if the keep-alive time on your side is longer than the server's. To fix this, you should implement a robust retry mechanism using a library like Apache HttpClient or Resilience4j. Also, ensure you are properly closing your input streams in a finally block to prevent resource leaks that might trigger the server to reset the connection.
Have you checked if there is a load balancer or firewall between your app and the API? Sometimes these intermediate layers kill "idle" connections silently, leading to a reset when you finally try to send data.
This error can also occur if the payload is too large and the server cuts the connection mid-stream. Check the server-side logs for "Request Entity Too Large" or similar warnings.
I agree with William. I’ve seen this happen with file uploads where the buffer size wasn't configured correctly on the server-side, causing an abrupt TCP reset.
That’s exactly what was happening! Our AWS Load Balancer had a 60-second idle timeout, but my Java app was trying to reuse connections for up to 5 minutes. I reduced the connection pool's max-idle time to 45 seconds, and the "Connection reset" errors have completely vanished. Thanks for the lead, Robert!