10.0 “Alis volat propriis”
Autoprefixer 10 is based on top of PostCSS 8 (check Known Issues section before updating).
Node.js 6.x, 8.x, 11.x support was removed.
Now you need to install Autoprefixer by npm install --save-dev autoprefixer postcss. We moved postcss from dependencies to peerDependencies according to new PostCSS plugin guidelines.