'Cant load a react app after starting server

(node:13176) [DEP_WEBPACK_DEV_SERVER_ON_AFTER_SETUP_MIDDLEWARE] DeprecationWarning: 'onAfterSetupMiddleware' option is deprecated. Please use the 'setupMiddlewares' option. (Use node --trace-deprecation ... to show where the warning was created) (node:13176) [DEP_WEBPACK_DEV_SERVER_ON_BEFORE_SETUP_MIDDLEWARE] DeprecationWarning: 'onBeforeSetupMiddleware' option is deprecated. Please use the 'setupMiddlewares' option

React is loading continuously after starting server

Solution 1:^[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:^[2]

I had the same error.

An authentication middleware, in my case AWS Amplify Auth, was changed incorrectly and my webpack config yielded an error. The fix for me was to re-install clean then debug the error.

So delete package-lock.json, delete the node-modules folder, and reinstall with "npm i".

Although this does not get to the root of the issue it should work to at least bring up the Dev Server to view any errors.

Solution 3:^[3]

I had the same issue. The problem was with the setupProxy.js.

If your setupProxy.js files look like below

const proxy = require('http-proxy-middleware');

module.exports = function(app) {
  app.use(proxy('/proxypath', { target: '<target path>' }));
};

Change it as below

const { createProxyMiddleware } = require('http-proxy-middleware');

module.exports = function(app) {
  app.use(createProxyMiddleware('/proxypath', { target: '<target path>' }));
};

As in the error, you have quoted, onAfterSetupMiddleware and onBeforeSetupMiddleware have been deprecated therefore the proxy method is not working as expected. So when you start the server with npm start the browser tries to redirect to the proxy URL. That's why you see as the react app is not loading.

Solution 4:^[4]

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

Solution 5:^[5]

What fixed it for me was running npm i webpack-dev-middleware.

Solution 6:^[6]

I faced the same error while adding a proxy middleware npm package to a react project. The warning was successfully resolved by running. npm audit fix --force

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1
Solution 2
Solution 3	Umayanga Gunawardhana
Solution 4	sushitrash
Solution 5	richardec
Solution 6	Nouveau

'Cant load a react app after starting server

Solution 1:[1]

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