r3f v9 (react 19) error in Effectcomposer

[chrisweb]

I created a reproduction repository for an error in the react postprocessing effectcomposer when using the latest r3f v9 beta 1 package (as well as next.js 15 / react 19)

The error message that gets catched by Next.js is the following:

TypeError: Cannot read properties of undefined (reading 'length')

which corresponds to line 139 https://github.com/pmndrs/react-postprocessing/blob/master/src/EffectComposer.tsx#L139 in the typescript source file

I wasn't sure if this repository is the right place to open an issue, as r3f v9 transitioned to a reconciler (previously core renderer) due to heavy changes in react 19, I assume the problem in the effectcomposer might be related to those changes

[ChronoByteCosmonaut]

Same issue 👍

[VrTech]

We might need to consider updating Effectcomposer to match react 19 as well 👍

[Priyansh4444]

The error message I am getting with children?
TypeError: children2 is undefined
"@react-three/drei": "^9.117.3",
"@react-three/fiber": "^9.0.0-alpha.8",
"@react-three/postprocessing": "^2.16.3",
"next": "^15.0.3",
"react": "^19.0.0-rc.1",

          <EffectComposer>
        <Bloom
          mipmapBlur
          levels={3}
          opacity={0.25}
          intensity={0.5}
          luminanceThreshold={0.31}
          luminanceSmoothing={0.71}
        />
      </EffectComposer>

Anything I could do?

[teneburu]

same issue !
TypeError: children2 is undefined
"@react-three/drei": "9.120.0",
"@react-three/fiber": "9.0.0-rc.1",
"@react-three/postprocessing": "^2.16.3",
"next": "^15.0.4",
"react": "^19.0.0-rc.1",

please help 🙏