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JavaScript

What is a Socket Hang Up?

← Errors

The 'socket hang up' error occurs in Node.js when an HTTP connection is closed by the server before a complete response is received. It is closely related to ECONNRESET and typically means the server closed the socket prematurely.

Why it happens

  • •The server closes the connection before finishing the response body.
  • •A reverse proxy (nginx, load balancer) times out and terminates the connection.
  • •The server crashes while processing the request.
  • •Not draining the request body on the server side causes the client to time out.

Examples

JavaScript

Code that triggers the error

const http = require("http");
const req = http.get("http://example.com/api", (res) => {
  res.resume();
});
req.end();
// Server closes connection before sending full response

Error output

Error: socket hang up
    code: 'ECONNRESET'

How to fix it

Always attach an 'error' event handler to Node.js HTTP requests. Implement retry logic for idempotent requests. Check server-side logs to determine why the connection is being closed early. Increase proxy timeout settings if the server needs more processing time.

Fixed code

const http = require("http");
const req = http.get("http://example.com/api", (res) => {
  let body = "";
  res.on("data", (chunk) => { body += chunk; });
  res.on("end", () => console.log(body));
});
req.on("error", (err) => {
  console.error("Request failed:", err.message);
});

Related errors

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