Does anyone know how to handle the CORS pre-flight OPTIONS request when initializing the Genesys Cloud Web Messaging SDK inside a Next.js 14 App Router component? I am building a custom trigger in Zapier to capture guest chat transcripts, but the frontend integration is blocking the initial handshake.
I am using the @genesyscloud/web-messaging-sdk in a client component. The configuration looks standard:
import { initMessaging } from '@genesyscloud/web-messaging-sdk';
export default function ChatWidget() {
useEffect(() => {
initMessaging({
mpid: 'my-mpid-here',
region: 'us-east-1',
onSessionStart: (session) => {
// Webhook call to Zapier
}
});
}, []);
return null;
}
The browser console throws: Access to XMLHttpRequest at 'https://webchat.genesis.com/v1/conversations' from origin 'http://localhost:3000' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.
I read this in the integration guide:
“The Web Messaging SDK handles all API communication via server-side proxies to avoid client-side CORS issues. Ensure your deployment environment allows outbound HTTPS traffic to the Genesys Cloud endpoints.”
This implies the SDK should bypass browser CORS entirely by routing through their proxy layer, yet I see direct fetch attempts hitting webchat.genesis.com from the browser context in Next.js development mode. Is there a specific Next.js middleware configuration or next.config.js rewrite rule required to proxy these requests correctly during SSR/CSR hydration? I suspect the issue is related to how Next.js handles the initial client-side hydration versus the server-side render, causing the SDK to attempt a direct call before the proxy context is fully established. I need to get the session.id reliably to my Zapier webhook without this network error interrupting the flow. Any insights on configuring the Next.js environment to satisfy this pre-flight check or forcing the SDK to use a specific proxy endpoint?
Depends on your setup, but generally the issue isn’t CORS but how Next.js App Router handles client-side hydration and the SDK’s initialization timing. The @genesyscloud/web-messaging-sdk relies on window and DOM elements that aren’t available during server-side rendering. If you mount it in a non-client component, the pre-flight fails because the browser never gets the chance to make the actual request.
You must wrap the initialization in a useEffect hook within a Client Component. Ensure your deploymentId and organizationId are passed as props or from a safe environment variable.
'use client';
import { useEffect } from 'react';
import { WebMessengerClient } from '@genesyscloud/web-messaging-sdk';
export default function MessengerWidget() {
useEffect(() => {
const client = new WebMessengerClient({
deploymentId: process.env.NEXT_PUBLIC_GC_DEPLOYMENT_ID,
organizationId: process.env.NEXT_PUBLIC_GC_ORG_ID
});
client.start();
return () => client.stop();
}, []);
return <div id="genesys-messenger-container" />;
}
Verify that NEXT_PUBLIC_GC_DEPLOYMENT_ID is set correctly. The SDK handles its own CORS headers, so no proxy is needed if loaded on the client side.
The documentation actually says…
Does anyone know how to handle the CORS pre-flight OPTIONS request when initializing the Genesys Cloud Web Messaging SDK inside a Next.js 14 App Router component?
I ran into this exact issue last week while wiring up an Express middleware to handle webhook events from the messenger. The CORS errors are usually a red herring caused by server-side rendering attempts. The SDK requires window and document, which don’t exist on the server.
You need to ensure the component is strictly client-side and initialization happens after hydration. Use dynamic imports with ssr: false to bypass the server entirely.
import dynamic from 'next/dynamic';
const WebMessenger = dynamic(() => import('./WebMessengerClient'), {
ssr: false,
loading: () => <p>Loading chat...</p>,
});
export default function ChatWidget() {
return <WebMessenger />;
}
This prevents the pre-flight OPTIONS request from ever hitting the server during the initial render. If you still see CORS errors after this, check your next.config.js for any rewrite rules that might be intercepting the /genesys endpoints. Make sure those are excluded or passed through correctly.