denoland/deno · error · TypeError

ERR_MISSING_ARGS

ERR_MISSING_ARGS

Error message

The "options" or "port" or "path" argument must be specified

What it means

`Socket.prototype.connect()` requires a TCP `port` or an IPC `path` in the normalized options. The polyfill throws ERR_MISSING_ARGS when `options.port === undefined` and `options.path` is null or undefined. This check runs before any other connect logic, so host, family, or fd alone cannot satisfy it.

Source

Thrown at ext/node/polyfills/net.ts:1629

  }
}
ObjectSetPrototypeOf(Socket.prototype, Duplex.prototype);
ObjectSetPrototypeOf(Socket, Duplex);

Socket.prototype.connect = function (...args) {
  let normalized;

  if (ArrayIsArray(args[0]) && args[0][normalizedArgsSymbol]) {
    normalized = args[0];
  } else {
    normalized = _normalizeArgs(args);
  }

  const options = normalized[0];
  const cb = normalized[1];

  if (options.port === undefined && options.path == null) {
    throw new ERR_MISSING_ARGS(["options", "port", "path"]);
  }

  if (netClientSocketChannel.hasSubscribers) {
    netClientSocketChannel.publish({
      socket: this,
    });
  }

  if (this.write !== Socket.prototype.write) {
    this.write = Socket.prototype.write;
  }

  if (this.destroyed) {
    this._handle = null;
    this._peername = undefined;
    this._sockname = undefined;
  }

View on GitHub (pinned to 9ad36f7a2c)

Solutions

1. Pass `port` (number) or `path` (IPC socket path) in the connect options.
2. Give environment-derived ports a fallback: `Number(process.env.PORT ?? 8080)`.
3. Validate the options object for port/path before calling connect.
4. For already-open file descriptors, construct with `new net.Socket({ fd })` instead of calling connect.

Example fix

// before
socket.connect({ host: 'db.internal' });

// after
socket.connect({ host: 'db.internal', port: Number(process.env.DB_PORT ?? 5432) });

function connectOpts(opts) {
  if (opts.port === undefined && (opts.path === undefined || opts.path === null)) {
    throw new Error('connect needs options.port or options.path');
  }
  return opts;
}
socket.connect(connectOpts({ host, port }));

function hasConnectTarget(v: unknown): v is { port?: number; path?: string } & Record<string, unknown> {
  if (typeof v !== 'object' || v === null) return false;
  const o = v as Record<string, unknown>;
  return typeof o.port === 'number' || typeof o.path === 'string';
}

try {
  socket.connect(opts, cb);
} catch (err) {
  if (err?.code === 'ERR_MISSING_ARGS') {
    // config bug, not a runtime fault: report which field was missing
    throw new Error(`connect target missing: ${JSON.stringify(opts)}`, { cause: err });
  }
  throw err;
}

When it happens

Trigger: `socket.connect({ host: 'db.internal' })` with no port; `socket.connect({})`; `socket.connect({ port: undefined })` from a missing config value; `socket.connect({ fd: 3 })` — connect does not accept fd as its target (fd belongs to the constructor).

Common situations: A port read from `process.env.PORT` or a config file that is missing in one environment. Platform-conditional code that sets `path` only on Linux but runs on macOS too. Refactors that rename or drop the port field.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• ERR_INVALID_ARG_VALUE
• EPIPE
• Invalid port (expected number): ${maybePort}
• ERR_FS_CP_SOCKET
• ERR_HTTP_SOCKET_ASSIGNED

AI-assisted analysis of denoland/deno@9ad36f7a2c (2026-08-20). Data as JSON: /api/errors/42d8df514f145c7e. Report an issue: GitHub.