🐛 [BUG] - "property is not writable, js engine: hermes" - error with Expo SDK 53 + React 19 + pnpm monorepo

[dave-hf]

Description

Environment:

• Expo SDK: 53.0.23
• React: 19.0.0
• React Native: 0.79.5
• Metro: 0.82.5
• Node.js: 18+
• Package Manager: pnpm 9.12.0
• Platform: iOS Simulator, Android Emulator
• New Architecture: Enabled
• Hermes: Enabled

Description:

When running an Expo app with the above configuration in a pnpm monorepo, the app consistently
fails to start with the following Hermes engine error:

ERROR [runtime not ready]: TypeError: property is not writable, js engine: hermes
ERROR [runtime not ready]: Invariant Violation: "main" has not been registered. This can
happen if:

• Metro (the local dev server) is run from the wrong folder. Check if Metro is running, stop
  it and restart it in the current project.
• A module failed to load due to an error and AppRegistry.registerComponent wasn't called.,
  js engine: hermes
  ERROR ExceptionsManager should be set up after React DevTools to avoid console.error arguments
  mutation

Question:

Is this a known compatibility issue between Expo SDK 53, React 19, New Architecture, and pnpm
monorepos? The error suggests that some property is being marked as non-writable during React
DevTools initialization, which prevents the normal app registration flow.

Reproduction steps

Steps to Reproduce:

  1. Create a pnpm monorepo with Expo SDK 53
  2. Enable New Architecture (newArchEnabled: true)
  3. Configure React 19 with pnpm overrides:
  "pnpm": {
    "overrides": {
      "react": "^19.0.0",
      "react-dom": "^19.0.0",
      "@types/react": "^19.0.0"
    }
  }
  4. Set up Metro config for monorepo with symlink support:
  config.resolver.unstable_enableSymlinks = true;
  5. Run expo start and try to load the app

  Actual Behavior:
  App fails to initialize with "property is not writable" Hermes error, preventing
  AppRegistry.registerComponent from being called.

  Expected Behavior:
  App should start normally without Hermes property errors.

  Additional Context:

  - The error persists even when removing all workspace package imports and using only standard
  React Native components
  - The error appears to be related to the timing of React DevTools setup and property
  configuration in Hermes
  - We've tried:
    - ✅ Enabling Metro symlink support (unstable_enableSymlinks: true)
    - ✅ Using hoisted node-linker in .npmrc
    - ✅ Forcing consistent React versions via pnpm overrides
    - ✅ Aliasing React in Metro config to use single instance
    - ❌ None of these resolved the issue

  Relevant Configuration:

  {
    "packageManager": "pnpm@9.12.0",
    "pnpm": {
      "overrides": {
        "metro": "^0.82.0",
        "metro-config": "^0.82.0",
        "metro-resolver": "^0.82.0",
        "react": "^19.0.0",
        "react-dom": "^19.0.0",
        "@types/react": "^19.0.0"
      }
    }
  }
  {
    "expo": {
      "newArchEnabled": true,
      "platforms": ["ios", "android", "web"]
    }
  }
  const { getDefaultConfig } = require('expo/metro-config');
  const config = getDefaultConfig(__dirname);

  config.resolver.unstable_enablePackageExports = false;
  config.resolver.unstable_enableSymlinks = true;
  config.resolver.alias = {
    'react': path.resolve(projectRoot, 'node_modules/react'),
    'react-native': path.resolve(projectRoot, 'node_modules/react-native'),
  };
  // monorepo configuration...
  

Logs

ERROR  ExceptionsManager should be set up after React DevTools to avoid console.error arguments mutation
 ERROR  [runtime not ready]: TypeError: property is not writable, js engine: hermes
 ERROR  [runtime not ready]: TypeError: property is not writable, js engine: hermes
 ERROR  [runtime not ready]: Invariant Violation: "main" has not been registered. This can happen if:
* Metro (the local dev server) is run from the wrong folder. Check if Metro is running, stop it and restart it in the current project.
* A module failed to load due to an error and `AppRegistry.registerComponent` wasn't called., js engine: hermes
➜  expo-app git:(main) ✗

Browsers

No response

OS

Mac