A clear path forward
How do I fix CORS errors in my published Replit app?
A cross-origin resource sharing (CORS) error means your frontend and backend use different web origins, and the backend has not allowed the frontend.
If both are part of the same app, use relative request URLs such as /api/endpoint. That keeps the requests on the same origin.
If they use different origins, configure the backend to allow the frontend's origin. For an Express app using the cors middleware, the setting looks like this:
app.use(cors({ origin: "https://your-frontend.replit.app" }));
Replace the example address with your frontend's actual origin. This is a middleware setting, not a complete server.
Before publishing, allow only the specific origins you need. See Troubleshooting deployments.
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