Module build failed when using mini-css-extract-plugin with postcss-loader for less

[Sergio]

• webpack 5.37.1
• mini-css-extract-plugin 1.6.0
• postcss-loader 5.3.0
• less 4.1.1

Expected Behavior

Build success.

Actual Behavior

This is the same problem as bug#522. But I don't know how he solved it. So can you give some answers? Thanks~

ERROR in ./src/views/app.vue?vue&type=style&index=0&lang=less& (./node_modules/mini-css-extract-plugin/dist/loader.js!./node_modules/css-loader/dist/cjs.js??clonedRuleSet-7[0].rules[0].use[1]!./node_modules/vue-loader/lib/loaders/stylePostLoader.js!./node_modules/postcss-loader/dist/cjs.js??clonedRuleSet-7[0].rules[0].use[2]!./node_modules/less-loader/dist/cjs.js??clonedRuleSet-7[0].rules[0].use[3]!./node_modules/vue-loader/lib/index.js??vue-loader-options!./src/views/app.vue?vue&type=style&index=0&lang=less&)
Module build failed (from ./node_modules/mini-css-extract-plugin/dist/loader.js):
ModuleBuildError: Module build failed (from ./node_modules/postcss-loader/dist/cjs.js):
TypeError: node.getIterator is not a function
at LazyResult.visitTick (E:\demo\node_modules\postcss\lib\lazy-result.js:522:33)
at LazyResult.runAsync (E:\demo\node_modules\postcss\lib\lazy-result.js:402:30)
at async Object.loader (E:\demo\node_modules\postcss-loader\dist\index.js:87:14)
at processResult (E:\demo\node_modules\webpack\lib\NormalModule.js:700:19)
at E:\demo\node_modules\webpack\lib\NormalModule.js:806:5
at E:\demo\node_modules\loader-runner\lib\LoaderRunner.js:399:11
at E:\demo\node_modules\loader-runner\lib\LoaderRunner.js:251:18
at context.callback (E:\demo\node_modules\loader-runner\lib\LoaderRunner.js:124:13)
at Object.loader (E:\demo\node_modules\postcss-loader\dist\index.js:96:7)
@ ./src/views/app.vue?vue&type=style&index=0&lang=less& 1:0-482 1:0-482
@ ./src/views/app.vue 4:0-64
@ ./src/main.js 7:0-32 28:13-20

Code

exports.cssLoaders = function (options) {
    options = options || {}

    const cssLoader = {
        loader: 'css-loader',
        options: {
            sourceMap: options.sourceMap
        }
    }

    const postcssLoader = {
        loader: 'postcss-loader',
        options: {
            sourceMap: options.sourceMap
        }
    }

    // generate loader string to be used with extract text plugin
    function generateLoaders (loader, loaderOptions) {
        const loaders = []

        // Extract CSS when that option is specified
        // (which is the case during production build)
        if (options.extract) {
            loaders.push(MiniCssExtractPlugin.loader)
        } else {
            loaders.push('vue-style-loader')
        }

        loaders.push(cssLoader)

        if (options.usePostCSS) {
            loaders.push(postcssLoader)
        }

        if (loader) {
            loaders.push({
                loader: loader + '-loader',
                options: Object.assign({}, loaderOptions, {
                    sourceMap: options.sourceMap
                })
            })
        }

        return loaders
    }
    return {
        css: generateLoaders(),
        postcss: generateLoaders(),
        less: generateLoaders('less'),
        sass: generateLoaders('sass', {
            indentedSyntax: true
        }),
        scss: generateLoaders('sass'),
        stylus: generateLoaders('stylus'),
        styl: generateLoaders('stylus')
    }
}

Reproduce

The main(utils.js) code is above.

vue-loader.conf.js

module.exports = {
    loaders: utils.cssLoaders({
        sourceMap: sourceMapEnabled,
        extract: isProduction
    }),
    cssSourceMap: sourceMapEnabled,
    cacheBusting: config.dev.cacheBusting,
    transformToRequire: {
        video: 'src',
        source: 'src',
        img: 'src',
        image: 'xlink:href'
    }
}

webpack.base.conf.js

module.exports = {
module: {
        rules: [
            {
                test: /\.vue$/,
                loader: 'vue-loader',
                options: vueLoaderConfig
            }
        ]
    },
}

webpack.prod.conf.js

const webpackConfig = merge(baseWebpackConfig, {
    module: {
        rules: utils.styleLoaders({
            sourceMap: config.build.productionSourceMap,
            extract: true,
            usePostCSS: true
        })
    }
}

The command to run is cross-env NODE_ENV=production node webpack.prod.conf.js

[Alexander Akait]

To get answer please fill out all fields in the issue template - provide steps to reproduce.

[Sergio]

To get answer please fill out all fields in the issue template - provide steps to reproduce.

I have updated the reproduction process. If it is not detailed enough, I will update again. Thanks

[Alexander Akait]

Can you provide package.json file?

[Sergio]

Can you provide package.json file?

{
  "name": "demo",
  "version": "1.0.0",
  "description": "",
  "private": true,
  "scripts": {
    "dev": "cross-env BABEL_ENV=development NODE_ENV=development webpack server --inline --progress --config build/webpack.dev.conf.js",
    "start": "npm run dev",
    "build:prod": "cross-env NODE_ENV=production env_config=prod node build/webpack.prod.conf.js",
    "build:test": "cross-env NODE_ENV=testing env_config=test node build/webpack.test.conf.js"
  },
  "author": "",
  "dependencies": {
    "clipboard": "^2.0.8",
    "crypto-js": "^4.0.0",
    "js-md5": "^0.7.3",
    "qiniu-js": "^3.2.0"
  },
  "devDependencies": {
    "@babel/core": "^7.14.3",
    "@babel/plugin-proposal-class-properties": "^7.13.0",
    "@babel/plugin-proposal-decorators": "^7.14.2",
    "@babel/plugin-proposal-export-namespace-from": "^7.14.2",
    "@babel/plugin-proposal-function-sent": "^7.12.13",
    "@babel/plugin-proposal-json-strings": "^7.14.2",
    "@babel/plugin-proposal-numeric-separator": "^7.14.2",
    "@babel/plugin-proposal-throw-expressions": "^7.12.13",
    "@babel/plugin-syntax-dynamic-import": "^7.8.3",
    "@babel/plugin-syntax-import-meta": "^7.10.4",
    "@babel/plugin-syntax-jsx": "^7.12.13",
    "@babel/plugin-transform-runtime": "^7.14.3",
    "@babel/preset-env": "^7.14.2",
    "autoprefixer": "^10.2.5",
    "babel-loader": "^8.2.2",
    "babel-upgrade": "^1.0.1",
    "chalk": "^4.1.1",
    "clean-webpack-plugin": "^4.0.0-alpha.0",
    "copy-webpack-plugin": "^9.0.0",
    "cross-env": "^7.0.3",
    "css-loader": "^5.2.6",
    "file-loader": "^6.2.0",
    "friendly-errors-webpack-plugin": "^1.7.0",
    "html-webpack-plugin": "^5.3.1",
    "less": "^4.1.1",
    "less-loader": "^9.0.0",
    "mini-css-extract-plugin": "^1.6.0",
    "node-notifier": "^10.0.0",
    "optimize-css-assets-webpack-plugin": "^6.0.0",
    "ora": "^5.4.0",
    "portfinder": "^1.0.28",
    "postcss": "^8.3.0",
    "postcss-import": "^14.0.2",
    "postcss-loader": "^5.3.0",
    "postcss-px2rem-exclude": "0.0.6",
    "postcss-url": "^10.1.3",
    "px2rem-loader": "^0.1.9",
    "rimraf": "^3.0.2",
    "script-ext-html-webpack-plugin": "^2.1.5",
    "script-loader": "^0.7.2",
    "semver": "^7.3.5",
    "shelljs": "^0.8.4",
    "url-loader": "^4.1.1",
    "vue-loader": "^15.9.7",
    "vue-style-loader": "^4.1.3",
    "vue-template-compiler": "^2.6.12",
    "webpack": "^5.37.1",
    "webpack-bundle-analyzer": "^4.4.2",
    "webpack-cli": "^4.7.0",
    "webpack-dev-server": "^3.11.2",
    "webpack-merge": "^5.7.3"
  },
  "engines": {
    "node": ">= 4.0.0",
    "npm": ">= 3.0.0"
  },
  "browserslist": [
    "> 1%",
    "last 2 versions",
    "not ie <= 8"
  ]
}

[Sergio]

I found the postcss plugin postcss-px2rem-exclude that caused the error.
Thanks for your answer.