React 18.2 in peerDependencies — is it compatible with Next.js 15 which requires React 19?

[kzgzhn]

Summary

I noticed that the peerDependencies for React in the Next.js package still specify version 18.2. However, according to the release notes, Next.js 15 is based on React 19. This seems like a potential mismatch.

https://github.com/vercel/next.js/blob/v15.4.5/packages/next/package.json#L113-L114

Could this be a mistake in the package.json file? Or is React 18.2 still considered valid for certain scenarios within Next.js 15?

If using React 18.2 is intentional, could you please clarify in which cases it’s appropriate or officially supported?

Thanks! 🙂

Additional information

No response

Example

No response

[icyJoseph]

Hi, App Router internally uses the react@canary channel. IIRC the 18 peerDependency marker there is for Pages Router.

• https://nextjs.org/blog/next-15#react-19
• https://nextjs.org/docs#react-version-handling