Cant load a react app after starting server

Solution 1:

This is a deprecation warning, meaning that you need to start using the newly suggested way of configuring your middleware. Instead of onBeforeSetupMiddleware and onAfterSetupMiddleware, use the setupMiddlewares-property.

The documentation itself can be found on Webpack's website (in this case here: https://webpack.js.org/configuration/dev-server/#devserversetupmiddlewares)

The configuration will look something like this (coming from onBeforeSetupMiddleware and onAfterSetupMiddleware):

setupMiddlewares: (middlewares, devServer) => {
    middleware1(devServer.app)
    middleware2(devServer.app)

    return middlewares
},

Another useful way of fixing this issue is by looking at the code others have written to fix this issue. I found this example to be helpful: https://github.com/facebook/docusaurus/pull/6168

Solution 2:

It's just a deprecation warning from one of the libraries you used within the app, have you tried to open http://localhost:3000 on your local? it is supposed to be running fine