sveltejs/kit · error · Error

Could not determine clientAddress

Error message

Could not determine clientAddress

What it means

The dev server builds a `RequestEvent` with a `getClientAddress()` callback that reads `req.socket.remoteAddress`. If the socket has no remote address (e.g. already destroyed, or an unusual socket/handler setup), the callback throws this error instead of returning a bogus address.

Source

Thrown at packages/kit/src/exports/vite/dev/index.js:431

							.replace(/%sveltekit\.status%/g, String(status))
							.replace(/%sveltekit\.error\.message%/g, escape_html(message));
					};

					res.writeHead(500, {
						'Content-Type': 'text/html; charset=utf-8'
					});
					res.end(
						error_template({ status: 500, message: manifest_error.message ?? 'Invalid routes' })
					);

					return;
				}

				const rendered = await server.respond(request, {
					getClientAddress: () => {
						const { remoteAddress } = req.socket;
						if (remoteAddress) return remoteAddress;
						throw new Error('Could not determine clientAddress');
					},
					read: (file) => {
						if (file in manifest.server_assets) {
							return fs.readFileSync(from_fs(file));
						}

						return fs.readFileSync(path.join(svelte_config.files.assets, file));
					},
					before_handle: async (event, config, prerender, handle) => {
						// we need to use .run because .enterWith() is not supported in Cloudflare Workers
						// see https://blog.cloudflare.com/workers-node-js-asynclocalstorage/
						return await async_local_storage.run({ event, config, prerender }, handle);
					},
					emulator
				});

				if (rendered.status === 404) {
					// @ts-expect-error

View on GitHub (pinned to 03f1687fe6)

Solutions

1. Guard request handling so aborted requests are not responded to
2. Check middleware/proxy setup that may detach the socket from the request
3. Upgrade SvelteKit/Vite — later versions handle aborted dev requests more gracefully
4. If you need the client IP, ensure the connection is a normal TCP socket (not a custom transport)

// caller-side check before reading the address
const addr = req.socket?.remoteAddress;
if (!addr) {
  // request socket is gone; skip responding
  return;
}

function hasClientAddress(socket) {
  return typeof socket?.remoteAddress === 'string' && socket.remoteAddress.length > 0;
}

try {
  await render(request);
} catch (err) {
  if (/Could not determine clientAddress/.test(err.message)) {
    // request aborted before response; safe to ignore
    return;
  }
  throw err;
}

When it happens

Trigger: Request handled after the underlying socket was closed/destroyed, so `remoteAddress` is undefined; proxying or custom server plumbing that replaces the normal http socket; early-aborted requests.

Common situations: Client cancels a request mid-render; high-frequency polling with aborts; running behind unusual Unix-socket or in-memory transports where remoteAddress is not set.

Related errors

• Cannot read clientAddress during prerendering
• Cannot read clientAddress during prerendering
• Could not determine clientAddress
• The configured Vite SSR environment must be a RunnableDevEnv
• ${__SVELTEKIT_ADAPTER_NAME__} does not specify getClientAddr

AI-assisted analysis of sveltejs/kit@03f1687fe6 (2026-09-02). Data as JSON: /api/errors/45d2c56df81ad639. Report an issue: GitHub.