Nitro HybridView "View config getter callback" error on Expo (Android)

[mckenytech]

I'm using Nitro Modules in an Expo project (SDK 54, RN 0.81.5, react-native-nitro-modules ^0.31.10).

• HybridObjects work perfectly ✅ - I can call C++ methods like HybridMathC.add(5, 3) and get results.
• HybridView (GameView) does NOT work ❌ - When I try to render a Nitro View, I get:

  Invariant Violation: View config getter callback for component `GameView` must be a function (received `undefined`).
  

And sometimes:

Tried to register two views with the same name GameView

My setup:

• GameView.nitro.ts spec with HybridView<GameViewProps, GameViewMethods>
• HybridGameViewView.kt implementing HybridGameViewSpec
• View manager registered in NitroRegameModulePackage.createViewManagers()
• getHostComponent('GameView', () => GameViewConfig) in TypeScript

What I've tried:

• Following official react-native-nitro-test package pattern exactly
• Using require() and ES6 import for the JSON config
• Adding @keep and @DoNotStrip annotations

Is Nitro HybridView compatible with Expo's Fabric setup? Or is there additional configuration needed?

[mrousavy]

Did you try restarting metro with clean cache? I for some reason cannot reproduce this at all.

[mrousavy]

I formatted your text for you. Next time please format your text so it is readable

[mrousavy]

Are you using a monorepo? Check your individual node_modules/ folders to make sure you don't have any modules duplicated (e.g. duplicate react/, react-native/ or react-native-nitro-modules/ could cause problems)

[deepanshu770]

getting same error in HybridView.
HybridObject is working fine.
Followed every step mentioned in docs
(Only Implemented Android Part cause Windows)

here is my example module-
https://github.com/deepanshu770/MyModule

[deepanshu770]

Team Please Look after it

[hannojg]

Hey @deepanshu770 thanks for providing a repo. Your repo is only the module, i don't see the react-native app that would run the module?
Can you add an example app to the module so we can reproduce?

Additionally, can you please run:

npm why react-native

and

npm why react

and confirm that the same react-native & react version is everywhere the same? (please share the output of the commands here, thanks!)

[deepanshu770]

Hey @hannojg Sorry for late response, I was quite busy last few day

here is the new repo with with modules and app -
https://github.com/deepanshu770/nitro-example

Here it output of commands

npm why react-native -

react-native@0.82.0
node_modules/react-native
  react-native@"0.82.0" from the root project

react-native@0.82.0 dev
../react-native-math/node_modules/react-native
  dev react-native@"0.82.0" from react-native-math@0.0.1
  ../react-native-math
    react-native-math@0.0.1
    node_modules/react-native-math
      react-native-math@"file:../react-native-math" from the root project

npm why react -

react@19.1.1
node_modules/react
  react@"19.1.1" from the root project

react@19.1.1 dev
../react-native-math/node_modules/react
  dev react@"19.1.1" from react-native-math@0.0.1
  ../react-native-math
    react-native-math@0.0.1
    node_modules/react-native-math
      react-native-math@"file:../react-native-math" from the root project

[hannojg]

Hey, this is related to your monorepo setup.
You have two node_modules/ folders, one in /react-native-math, one in /NitroTest, each with their own copy of react-native.
The problem is that there will be now two instances of the NativeComponentRegistry from react-native.

So the best way to address that is to properly configure the mono-repo setup to use workspaces, so that there is only one react-native module instance present.