webpack-dev-server fails to run with error of validateSchema - reactjs

Question

this is a react hello-world proj , on local machine win7, use npm download
packages, when run " webpack-dev-server --open " it has an error like these:
F:\now\react\setup\node_modules\webpack-cli\bin\convert-argv.js:7
const validateSchema = process.webpackModule.validateSchema;
TypeError: Cannot read property 'validateSchema' of undefined
...
screenshot about error info
this is the package.json and webpack.config.js
{
"name": "setup",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start": "webpack-dev-server --open"
},
"author": "",
"license": "ISC",
"dependencies": {},
"devDependencies": {
"babel-core": "^6.26.3",
"babel-loader": "^7.1.4",
"babel-preset-env": "^1.7.0",
"babel-preset-react": "^6.24.1",
"react": "^16.4.0",
"react-dom": "^16.4.0",
"webpack": "^4.10.2",
"webpack-cli": "^3.0.0",
"webpack-dev-server": "^3.1.4"
}
}
webpack.config.js:
const webpack = require('webpack');
module.exports = {
devServer: {
contentBase: "./src",
historyApiFallback: true,
inline: true
},
module: {
rules: [
{
test: /(\.jsx|\.js)$/,
use: {
loader: "babel-loader",
options: {
presets: [
"env", "react"
]
}
},
exclude: /node_modules/
}
]
}
}

Answer 1

The webpack-cli just bumped from v2 to v3 about 10 hours ago, and it looks like this might be a bug with v3. I haven't figured out an actual fix yet, but a temporary workaround is to downgrade to webpack-cli v2 by manually changing the version number in your package.json to ^2.0.0.
Hope that helps you get unstuck for the moment.