5.10.2: React 16 -> 17 upgrade, Webpack 4 warnings: "export 'Fragment' (imported as 'React') was not found in 'react'

[lkraav]

Multiple warnings for various standard React imports (Fragment, createContext, forwardRef, etc), sample traceback:

WARNING in /app/node_modules/@emotion/react/dist/emotion-react.esm.js 286:42-56
2025-12-11T22:47:36.452314673Z "export 'Fragment' (imported as 'React') was not found in 'react'
2025-12-11T22:47:36.452318815Z  @ /app/node_modules/react-select/creatable/dist/react-select-creatable.esm.js
2025-12-11T22:47:36.452323153Z  @ ./lib/components/select/select.jsx
2025-12-11T22:47:36.452327489Z  @ ./lib/components/select/index.js
2025-12-11T22:47:36.452331440Z  @ ./lib/components/table/table.jsx
2025-12-11T22:47:36.452335295Z  @ ./lib/components/table/index.js
2025-12-11T22:47:36.452339161Z  @ ./pages/home/components/tests-table.jsx
2025-12-11T22:47:36.452343119Z  @ ./pages/home/home.jsx
2025-12-11T22:47:36.452346993Z  @ ./pages/home/index.js
2025-12-11T22:47:36.452350796Z  @ ./app.jsx
2025-12-11T22:47:36.452354677Z  @ ./index.jsx
2025-12-11T22:47:36.452360649Z  @ multi /app/node_modules/@pmmmwh/react-refresh-webpack-plugin/client/ReactRefreshEntry.js /app/node_modules/@pmmmwh/react-refresh-webpack-plugin/client/ErrorOverlayEntry.js?sockHost=0.0.0.0&sockPort=3004&sockProtocol=http ./index.jsx

On surface, it looks like emotion-js/emotion#2649 but it's not: there are no React 18 things involved here.

With a note "6. Upgrade to webpack 5 (Best Long-term), because it has native ESM support with fullySpecified: false", AI was able to silence warnings by installing Webpack 4 aliases like:

...
  resolve: {
  ...
    alias: {
      react: path.resolve(__dirname, '../../node_modules/react'),
      'react-dom': path.resolve(__dirname, '../../node_modules/react-dom'),
    },
...

Is this the actual correct solution on Webpack 4?

What is the source of this problem in the first place?

It triggers both with [email protected] and @5.10.2. Searches all across primary platforms deliver no applicable hits on this.

[lkraav]

Update: this is almost certainly to do with multiple package copies being loaded. Ran into the same situation on another build, where an accidental lib/node_modules copy confused webpack. Will re-attempt React update shortly and hopefully it'll be resolved.