Invalid Configuration Object in Webpack

Invalid configuration object. Webpack has been initialised using a configuration object that does not match the API schema

I don't exactly know what causes that, but I solve it this way.

Reinstall whole project but remember that webpack-dev-server must be globally installed.
I walk through some server errors like webpack cant be found, so I linked Webpack using link command.
In output Resolving some absolute path issues.

In devServer object: inline: false

webpack.config.js

module.exports = {
    entry: "./src/js/main.js",
    output: {
        path:__dirname+ '/dist/',
        filename: "bundle.js",
        publicPath: '/'
    },
    devServer: {
        inline: false,
        contentBase: "./dist",
    },
    module: {
        loaders: [
            {
                test: /\.jsx?$/,
                exclude:/(node_modules|bower_components)/,
                loader: 'babel-loader',
                query: {
                    presets: ['es2015', 'react']
                }
            }
        ]
    }

};

package.json

{
  "name": "react-flux-architecture-es6",
  "version": "1.0.0",
  "description": "egghead",
  "main": "index.js",
  "scripts": {
    "start": "webpack-dev-server"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/cichy/react-flux-architecture-es6.git"
  },
  "keywords": [
    "React",
    "flux"
  ],
  "author": "Jarosław Cichoń",
  "license": "ISC",
  "bugs": {
    "url": "https://github.com/cichy/react-flux-architecture-es6/issues"
  },
  "homepage": "https://github.com/cichy/react-flux-architecture-es6#readme",
  "dependencies": {
    "flux": "^3.1.2",
    "react": "^15.4.2",
    "react-dom": "^15.4.2",
    "react-router": "^3.0.2"
  },
  "devDependencies": {
    "babel-core": "^6.22.1",
    "babel-loader": "^6.2.10",
    "babel-preset-es2015": "^6.22.0",
    "babel-preset-react": "^6.22.0"
  }
}

Invalid configuration object: Webpack has been initialized using a configuration object that does not match the API schema

The error says that the value for "loader" should be a non-empty string. So if you look at the value for "loader", you see this:

loader: ExtractTextPlugin.extract(

I'm willing to bet that the above does not return a string. When looking at the docs for the ExtractTextPlugin, it says to use it like so:

use: ExtractTextPlugin.extract(

Invalid configuration object. Webpack has been initialized using a configuration object that does not match the API schema

I think it is case sensitive, ie. change the D to a d, change moduleIDs to moduleIds.

Webpack 5.47.1 : Invalid configuration object. Webpack has been initialized using a configuration object that does not match the API schema

mode should be in the root object and not in the module object:

module.exports = (options) => ({
    mode: 'development',
    entry: options.entry,
    output: Object.assign({ // Compile into js/build.js
        path: path.resolve(process.cwd(), 'build'),
        publicPath: '/',
    }, options.output), // Merge with env dependent settings
    module: {

        rules: [
            {
                test: /\.js$/,
                exclude: /node_modules/,
                use: {
                    loader: 'babel-loader',
                    options: options.babelQuery,
                },
            },
            {
                test: /\.scss$/,
                exclude: /node_modules/,
                use: ['style-loader', 'css-loader', 'sass-loader'],
            },
            {
                test: /\.css$/,
                exclude: /node_modules/,
                use: ['style-loader', 'css-loader'],
            },
            {
                test: /\.css$/,
                include: /node_modules/,
                use: ['style-loader', 'css-loader'],
            },
            {
                test: /\.(eot|svg|otf|ttf|woff|woff2)$/,
                use: 'file-loader',
            },
            {
                test: /\.(jpe?g|png|gif|svg)$/i,
                use: [
                    'file-loader',
                    {
                        loader: 'image-webpack-loader',
                        options: {
                            progressive: true,
                            optimizationLevel: 7,
                            interlaced: false,
                            pngquant: {
                                quality: '65-90',
                                speed: 4,
                            },
                        },
                    },
                ],
            },
            {
                test: /\.html$/,
                use: 'html-loader',
            },
            {
                test: /\.json$/,
                use: 'json-loader',
            },
            {
                test: /\.(mp4|webm)$/,
                use: {
                    loader: 'url-loader',
                    options: {
                        limit: 10000,
                    },
                },
            },
        ],
    },
    plugins: options.plugins.concat([
        new webpack.ProvidePlugin({
            // make fetch available
            fetch: 'exports-loader?self.fetch!whatwg-fetch',
        }),

        new webpack.DefinePlugin({
            'process.env.NODE_ENV': JSON.stringify('development'),
        }),
        // new webpack.NamedModulesPlugin(),
    ]),
    resolve: {
        modules: ['app', 'node_modules'],
        extensions: [
            '.js',
            '.jsx',
            '.react.js',
        ],
        mainFields: [
            'browser',
            'jsnext:main',
            'main',
        ],
    },
    devtool: options.devtool,
    target: 'web', // Make web variables accessible to webpack, e.g. window
    performance: options.performance || {},
});

ValidationError: Invalid configuration object. Webpack has been initialized using a configuration object that does not match the API schema. Next.js

After JDB's answer i had a clear hint. I configured my next.js app to use webpack4 after reading this. Here is my new next.cofig.js:

module.exports = {
  webpack5: false,
  webpack: (config) => {
    config.node = {
      dns: "mock",
      fs: "empty",
      path: true,
      url: false,
    };
    return config;
  },
};

webpack gives me error "Invalid configuration object. 'plugins'."

The configuration file has an error: the 'plugins' object should not be a child of 'module' but needd to be one hierachy level higher. (see webpack docs: https://webpack.js.org/configuration/)

Try:

const path = require('path')
const webpack = require('webpack')
const HtmlWebPackPlugin = require("html-webpack-plugin")
const MiniCssExtractPlugin = require('mini-css-extract-plugin')
const WorkboxPlugin = require('workbox-webpack-plugin')
module.exports = {
    entry: "./src/js/index.js",
    mode: 'production',
    output: {
        libraryTarget: 'var',
        library: 'Client'
    },
    module: {
        rules: [
            {
                test: '/\.js$/',
                exclude: /node_modules/,
                loader: "babel-loader"
            },
            {
                test:  /\.(png|woff|woff2|eot|ttf|svg)$/, loader: 'url-loader?limit=100000',
                use: [ MiniCssExtractPlugin.loader, 'css-loader', 'sass-loader' ]
            },
            {
                test: /\.(woff(2)?|ttf|eot|svg)(\?v=\d+\.\d+\.\d+)?$/,
                use: [{
                    loader: 'file-loader',
                    options: {
                      name: '[name].[ext]',
                      outputPath: 'fonts/'
                    }
                }]
             }
        ],  
    },   
    plugins: [
        new HtmlWebPackPlugin({
            template: "./src/index.html",
            filename: "./index.html",
        }),
        new MiniCssExtractPlugin({filename: '[name].css'}),
        new WorkboxPlugin.GenerateSW()
    ]
}

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