Use React 16 With Gatsby
Gatsby, the blazing fast static site generator for React, is tied to React 15.6. If you've been using React 16+ for a while, then this may come as a bit of a buzzkill.
Fortunately, there is a Gatsby plugin that lets you use React 16 with a Gatsby v1 site -- gatsby-plugin-react-next.
Add it the plugin as a dependency:
$ yarn add gatsby-plugin-react-next
Then add it to the list of plugins in