CORS Failure on Web Messaging SDK in Next.js SSR

I can’t seem to figure out why the Genesys Cloud Web Messaging SDK triggers a CORS error when initializing via the Guest API in a Next.js application during server-side rendering. The browser console reports Access-Control-Allow-Origin is missing when the widget attempts to handshake with https://api.mypurecloud.com/api/v2/conversations/messaging, despite the origin header being correctly set in the SDK configuration object.

Access to fetch at 'https://api.mypurecloud.com/api/v2/conversations/messaging' from origin 'https://myapp.vercel.app' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

The issue persists even when disabling Next.js hydration for the widget component. Is there a specific header or initialization sequence required for the Guest API to bypass strict CORS enforcement in a server-rendered context?

The CORS failure stems from Next.js SSR executing the SDK initialization on the server, which does not support browser-specific CORS headers. The Genesys Cloud Web Messaging SDK is designed for client-side execution only.

1. Ensure the SDK import and initialization occur strictly within a client-side component or a useEffect hook.
2. Verify the origin parameter matches the exact domain in the browser, including the protocol.

// Correct Client-Side Initialization
import { WebMessaging } from '@genesys/web-messaging-sdk';

useEffect(() => {
 if (typeof window !== 'undefined') {
 const client = new WebMessaging({
 origin: 'https://myapp.com',
 clientId: 'your-client-id'
 });
 client.init();
 }
}, []);

The documentation states: “The SDK must be initialized in a browser environment.” Server-side rendering bypasses the browser’s CORS preflight checks, causing the handshake to fail against api.mypurecloud.com.