Error: PostCSS plugin autoprefixer requires PostCSS 8. Update PostCSS or downgrade this plugin

Question

I am getting this error whenever I run npm start. I tried a couple of fixes but none of them work for me. I tried to change the version of autoprefixer to 9.8.6 but it didn\'t w

Answer 1

Quick fix

Downgrade your autoprefixer to version 9, use

"autoprefixer": "^9.0.0"

in your dev dependencies.

More details

PostCSS was updated to version 8, however, PostCSS CLI has not yet been updated to handle PostCSS plugins which use the new PostCSS 8+ API. Autoprefixer uses the new PostCSS 8 API since version 10.

This is documented under known issues in the PostCSS GitHub page.

Once PostCSS CLI is updated to handle plugins that use the new PostCSS 8+ API, this will likely not be an issue. But until then, you may need to downgrade some PostCSS plugins to avoid errors.