PostCSS plugin postcss-purgecss requires PostCSS 8.

Describe the bug Config PurgeCSS with Gridsome Vuejs and gets this error

Screenshots

Environment (please complete the following information):

• OS: Windows
• Packages: purgecss, postcss-loader, @fullhuman/postcss-purgecss, @fullhuman/vue-cli-plugin-purgecss
• Version:

   "postcss": "^8.2.9",
   "postcss-loader": "^5.2.0",
   "@fullhuman/postcss-purgecss": "^4.0.3",
   "@fullhuman/vue-cli-plugin-purgecss": "~4.0.3",

Additional context Config:

chainWebpack: config => {
    config.plugin('css').use(MiniCssExtractPlugin, [{
      filename: '[name].[hash].css',
    }])

    config.module
        .rule('css')
        .oneOf('normal')
        .use('postcss-loader')
        .tap(options => {
          options.plugins.unshift(...[
            require('cssnano'),
            purgecss({
              content: [`./public/**/*.html`, `./src/**/*.vue`],
              defaultExtractor(content) {
                const contentWithoutStyleBlocks = content.replace(
                    /<style[^]+?<\/style>/gi,
                    ""
                );
                return (
                    contentWithoutStyleBlocks.match(
                        /[A-Za-z0-9-_/:]*[A-Za-z0-9-_/]+/g
                    ) || []
                );
              },
              safelist: [
                /-(leave|enter|appear)(|-(to|from|active))$/,
                /^(?!(|.*?:)cursor-move).+-move$/,
                /^router-link(|-exact)-active$/,
                /data-v-.*/,
              ],
            })
          ])
          return options
        })

    config.performance.hints('warning')

  },

[amir-mln]

I had the same issue and nothing worked until i downgraded. npm i -D @fullhuman/postcss-purgecss@3.0.0 postcss@7.0.35

[Ffloriel]

PurgeCSS version >4 will work with PostCSS 8. You will need to use version 3.0.0 with PostCSS 7