1. Problem description

When configuring webpack.config.js to automatically package, an Error: Cannot find module’@babel/core’ error occurred. I
initially thought that babel-core was not installed. After reinstalling babel-core several times, it still doesn’t work. Compared with the previous project, it is found that the version of babel-loader is different. The previous one was @7.1.5 version, but now it is @8.0.0 version.

Second, the solution

Install back to the @7.1.5 version with a dubious mood

npm uninstall babel-loader
npm install babel-loader@7.1.5

And then npm run buildfound success!
I’m a little puzzled, it’s only a few days since the last installation, so I updated it to babel-loader@8.0.0. And it doesn’t support the original configuration anymore. No solution was found on the Internet, and the principle is still unclear. Mark it first, and after solving the problem of @8.0.0, I will come back to add.

Attach webpack.config.js code:

var webpack = require('webpack');
var path = require('path');
var HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {
    entry: __dirname + '/client/root/index', 
    output: {
        path: path.join(__dirname + '/dist'),
        filename: 'bundle.js',  
    },

    module: {
        loaders : [{
            test :/(\.jsx|\.js)$/,
            exclude : /node_modules/,
            loader :'babel-loader',
            options:{
                presets:[
                    "env", "react", 
                ]
            }
        },
        {
            test: /\.css$/,
            loader: 'style-loader!css-loader'
        },
        {
            test: /\.less$/,
            loader: 'style-loader!css-loader!less-loader'
        },
        {
            test: /\.(jpg|.png)$/,
            loader: 'url-loader'
        }
        ]
    },

    plugins: [
        new HtmlWebpackPlugin({
            template: __dirname + '/client/views/template.html'
        }),
    ]
}

Regarding the babel-loader@8.0.0cause of the error has been found, thank you @Sky__zt for your answer.
(Forgot to read the official document)

The official default babel-loader | babel corresponding version needs to be the same: that is, the babel-loaderlatest version is requiredbabel

For details, please refer to: “npm_babel-loader”

to sum up:

Two solutions: 1. Roll back the lower version

npm install -D babel-loader@7 babel-core babel-preset-env

2. Update to the highest version:

npm install -D babel-loader @babel/core @babel/preset-env webpack

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