# Fix PostCSS 'must export a plugins key' error in Next.js

> How to fix the Next.js error Your custom PostCSS configuration must export a plugins key by adding a postcss.config.json file with an empty plugins array.

Author: [Flavio Copes](https://flaviocopes.com/about/) | Published: 2022-07-15 | Topics: [Next.js](https://flaviocopes.com/tags/next/) | Canonical: https://flaviocopes.com/fix-postcss-export-plugins-key/

I updated an old [Next.js](https://flaviocopes.com/nextjs/) app and when I ran `npm run dev` I had this error:

```
error - ./node_modules/next/dist/build/webpack/loaders/css-loader/src/index.js??ruleSet[1].rules[2].oneOf[8].use[1]!./node_modules/next/dist/build/webpack/loaders/postcss-loader/src/index.js??ruleSet[1].rules[2].oneOf[8].use[2]!./styles/globals.css
Error: Your custom PostCSS configuration must export a `plugins` key.
```

I added a `postcss.config.json` file with this content:

```json
{
  "plugins": []
}
```

and the app started working again.