How to fix "componentWillMount has been renamed"

December 12, 2019

I was using the react-helmet package, and noticed an error in my console saying:

Warning: componentWillMount has been renamed, and is not recommended for use. See for details.

Turns out, in React 17 (the next version of React), the componentWillMount method will no longer work. react-helmet relies on this method, and therefore there's a warning when you try to use componentWillMount in React 16.9+.


There's a virtually identical package called react-helmet-async, which doesn't have this error and will continue working through React 17.

Installing and replacing react-helmet with react-helmet-async everywhere in my code got rid of the warning for me.

To install, run:

npm install react-helmet-async

And then use the new package just as you would use react-helmet:

import { Helmet } from "react-helmet-async"

// ... etc

Solving it in Gatsby

If your site is built with Gatsby, you're probably currently using gatsby-plugin-react-helmet. You'll need to replace this plugin with @rhysforyou/gatsby-plugin-react-helmet-async.

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