Node / GraphQL and Koa: address already in use :::3000 - graphql

Question

I am trying to implement GraphQL to my KoaJs server. However, every time nodemon restart on change, I will receive the errors in my console:
Error: listen EADDRINUSE: address already in use :::3000
at Server.setupListenHandle [as _listen2] (node:net:1334:16)
at listenInCluster (node:net:1382:12)
...
code: 'EADDRINUSE',
errno: -48,
syscall: 'listen',
address: '::',
port: 3000
}
[nodemon] app crashed - waiting for file changes before starting...
Here's my code:
import { ApolloServer, gql } from "apollo-server-koa";
import { ApolloServerPluginDrainHttpServer } from "apollo-server-core";
import Koa from "koa";
import http from "http";
const typeDefs = gql`
type Query {
hello: String
}
`;
const resolvers = {
Query: {
hello: () => "Hello world!",
},
};
async function startApolloServer() {
const httpServer = http.createServer();
const server = new ApolloServer({
typeDefs,
resolvers,
csrfPrevention: true,
cache: "bounded",
plugins: [ApolloServerPluginDrainHttpServer({ httpServer })],
});
await server.start();
const app = new Koa();
server.applyMiddleware({ app, path: "/graphql" });
httpServer.on("request", app.callback());
await new Promise<void>((resolve) =>
httpServer.listen({ port: 3000 }, resolve)
);
console.log(`🚀 Server ready at http://localhost:3000${server.graphqlPath}`);
return { server, app };
}
startApolloServer()
How can I fix the error?
Thanks for any help!!

Answer 1

I think you are trying to run on a port that is being used by another service or the same service in the background.
You can try:
You can find the service running on port 3000 and turn it off.
You can change the port you are using. For example, 5000.
To find service:
Windows:
netstat -ano -p tcp | find "3000"
Linux or MacOS
lsof -iTCP -sTCP:LISTEN -n -P | grep :3000
Kill service using the pid. Then run your server again.