Error: 'h' is not exported by node_modules/preact/dist/preact.umd.js

Hello,

We’re using Rollup with our preact application, however since the release of Preact 8.5.0 we receive the following error when building with rollup:

[!] Error: 'h' is not exported by node_modules/preact/dist/preact.umd.js
https://rollupjs.org/guide/en/#error-name-is-not-exported-by-module
src/Components/UI/index.tsx (1:20)
1: import { Component, h } from 'preact';

When we pin to 8.4.2 the build completes successfully. Looking at the comparison here I cannot see anything that could introduce breaking changes.

Kind regards,

Nathan

[developit]

Hi @preeny95 - it seems like your Rollup may be configured to look for a "browser" field in package.json, but not to actually handle the contents it points to. The "browser" field can never point to an ES Modules build.

Are you able to post your Rollup configuration? If not, what we’re looking for is where you’ve done something like:

// rollup.config.js
import resolve from 'rollup-plugin-node-resolve';
export default {
  plugins: [
    resolve({
      // you likely have this specified, which is incorrect:
      mainFields: ['browser', 'module', 'main'],

      // or this, which is also incorrect:
      browser: true,  
    })
  ]
}

Instead, you’ll want to do this:

// rollup.config.js
import resolve from 'rollup-plugin-node-resolve';
export default {
  plugins: [
    resolve({
-      mainFields: ['browser', 'module', 'main'],
+      mainFields: ['module', 'browser', 'main'],

-      browser: true,  
    })
  ]
}

[preeny95]

🎉 that’s done the trick it seems! Thank you!!