Uglify Js Plugin removed ,NPM START failed,React Js Errors

1.Error:

webpack.optimize.UglifyJsPlugin has been removed, please use config.optimization.minimize instead. (Reactjs, Webpack)

Solution:

Error Comes When We Migrating from Webpack 3 to 4

Run below command in case of npm start failed

 E:\Project\ui> npm install webpack@3.10.0

 E:\Project\ui>npm install webpack-dev-server@2.9.7

 E:\Project\ui> npm start

2.Error:

Error-in-node-modules-css-loader, Error-in-node-modules-sass-loader (Reactjs, Webpack)

Solution:

Description

open Command Prompt as Administrator & Run below command

 E:\Project\ui> npm rebuild node-sass

 E:\Project\ui> npm start

Note- Since my project location was "E:\Project\ui>"
we run commands from that location. You can use your project location. In "ui" folder i have "src, package.json, node_modules, webpack-config.js"