`req.body` is not set when using Apollo Server with Express – Middleware issue?

I'm learning GraphQL and trying to set up Apollo Server with Express (v4), but I keep getting the following error when making a request to /graphql:

req.body is not set; this probably means you forgot to set up the `json` middleware before the Apollo Server middleware.

Here's my server code:

const express = require("express");
const { ApolloServer } = require('@apollo/server');
const { expressMiddleware } = require('@apollo/server/express4')
const cors = require('cors');

async function startServer() {
    const app = express();

    const server = new ApolloServer({
        typeDefs: `
            type Todo {
                id: ID!
                title: String!
                completed: Boolean!
            }
            
            type Query {
                getTodos: [Todo]
            }
        `,
        resolvers: {
            Query: {
                getTodos: () => []
            }
        }
    });

    await server.start();

    app.use('/graphql', cors(), express.json(), expressMiddleware(server));

    const PORT = process.env.PORT || 8000;
    await new Promise((resolve) => app.listen(PORT, resolve));
    console.log(`Server is running on port ${PORT}`);
}

startServer().catch((err) => {
    console.error('Error starting the server:', err);
});

I've added express.json() before the expressMiddleware, but the error persists. Is there something I'm missing when using Apollo Server with Express 4 middleware?

Any help is appreciated!

if you are trying to open this http://localhost:8000/graphql in browser tab then it'll show that warning instead use postman or any other api tester and hit a post req at http://localhost:8000/graphql using some queries then it'll work. cauz browser page is sending get req instead post and without Content-Type: application/json that's why it is giving this error (req.body is not set; this probably means you forgot to set up the json middleware before the Apollo Server middleware.)