React 19 compatibility issue?

[Nickk4]

The library was working perfectly but after upgrading from React 18 to 19, I get the error:

Error: A React Element from an older version of React was rendered. This is not supported. It can happen if:
•	Multiple copies of the "react" package is used.
•	A library pre-bundled an old copy of "react" or "react/jsx-runtime".
•	A compiler tries to "inline" JSX instead of using the runtime. at throwOnInvalidObjectType (react-dom-client.development.js:4442:15) at reconcileChildFibersImpl (react-dom-client.development.js:5376:11) at react-dom-client.development.js:5415:33 at reconcileChildren (react-dom-client.development.js:7738:13) at updateClassComponent (react-dom-client.development.js:8603:13) at beginWork (react-dom-client.development.js:9697:13) at runWithFiberInDEV (react-dom-client.development.js:543:16) at performUnitOfWork (react-dom-client.development.js:15044:22) at workLoopSync (react-dom-client.development.js:14870:41) at renderRootSync (react-dom-client.development.js:14850:11)

The above error occurred in the <Ao> component.

React will try to recreate this component tree from scratch using the error boundary you provided, RenderErrorBoundary. Error Component Stack at Ao (customScroll.tsx:141:5) at Scroll (index.tsx:15:19) at IndexPage (index.tsx:13:1)

[rommguy]

Thanks, I actually upgraded it already to React 18 and checked it there - are you sure this error appears on both 18 and 19
I can try to upgrade to 19 as well, it will take me a few weeks though.
You're welcome to create a PR for that

[Nickk4]

I'm a bit new to this, but I think (part of) the problem is that the build of react-custom-scroll includes ReactDebugCurrentFrame, which React 19 doesn't like. If I build your library using React 19, these references are not there.

P.S. The error is only there on React 19. It worked all fine for me on React 18.

I think it might be solved if you replace in package.json:

"dependencies": {
  "react": "^18.2.0",
  "react-dom": "^18.2.0"
}

with:

"peerDependencies": {
  "react": ">=18.0.0",
  "react-dom": ">=18.0.0"
},
"devDependencies": {
  "react": "^18.2.0",
  "react-dom": "^18.2.0"
}

[tecoad]

Yep, i confirm doesnt not work on react 19:

Error: Cannot read properties of undefined (reading 'ReactCurrentDispatcher') at

4 | import { CustomScroll } from 'react-custom-scroll'

[biggyspender]

This is mainly because this package accidentally bundles all of react 18 in the distributable. @rommguy , in your bundling process, react should be marked as external and not included in the package itself.

See https://vite.dev/guide/build#library-mode