npm WARN npm npm does not support Node.js v9.1.0

Uninstall the global instance of npm:

npm uninstall -g npm

This will cause your system to fall back on the version of npm installed by node 9.1.0 and the warning will disappear.

It turns out that the current installed npm is not compatible with the new node and has a hard time updating.

The solution is to uninstall npm and then reinstall node which will contain the correct version of npm.

Here's how:

1. Uninstall npm.

   Mac:
   sudo npm uninstall -g npm
   
   Windows:
   npm uninstall -g npm
   

2. Install node from https://nodejs.org