Estoy tratando de configurar fastify-socket.io, fastify-cors, pero sigo recibiendo errores CORS.

Tengo fastify-cors y fastsity-socket.io registrados

 Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://localhost:5000/socket.io/?EIO=4&transport=polling&t=NoUUJ6g. (Reason: CORS header 'Access-Control-Allow-Origin' missing).

Aquí está el código de back-end:

 import fastify from "fastify"; import fastifyIO from "fastify-socket.io"; import fastifyCors from "fastify-cors"; const server = fastify();'' const PORT = 5000; server.register(fastifyIO); server.register(fastifyCors), { origin: "*", methods: "GET,POST,PUT,PATCH,DELETE", }; server.listen(PORT, () => { console.log(`Server running on port:${PORT}`); }); server.get("/", (request, reply) => { reply.status(200).send({ ServerOnline: true }); }); server.ready().then(() => { server.io.on("connection", (socket) => { console.log("user connected" + socket.id); socket.on("message", (data) => { console.log(data); }); }); });

Aquí está el código frontal:

 import "./App.css"; import { io } from "socket.io-client"; function App() { const sendData = () => { const socket = io("http://localhost:5000"); socket.on("connection"); const sendMessage = () => { socket.emit("message", "hey it worked!"); }; sendMessage(); }; return ( <div className="app-container"> <h1>Socket.IO</h1> <button onClick={sendData}>Send</button> </div> ); } export default App;

No estoy seguro de por qué recibo estos Cors Errors. Creo que tiene algo que ver con fastify-socket.io