Thread 6: "Exception NSException * "Unhandled JS Exception: Error: invalid host, js engine: hermes" about hermes

[nishadthajudeen001]

Reactotron was causing the issue in release mode, I was able to fix that by commenting out the reactotron code during the release build.

[liylmn]

Reactotron was causing the issue in release mode, I was able to fix that by commenting out the reactotron code during the release build.

Could you please elaborate on the same issue，thanks @nishadthajudeen001

Only the Release version APP was crashing with this error for us -"Error: invalid host, js engine: hermes",

This issue got resolved when we took the release after commenting out the Reactotron code.

bro, thank you so much. Just delete these few libraries
reactotron-react-native
reactotron-redux
reactotron-redux-saga

[nishadthajudeen001]

Reactotron was causing the issue in release mode, I was able to fix that by commenting out the reactotron code during the release build.

Could you please elaborate on the same issue，thanks @nishadthajudeen001

Only the Release version APP was crashing with this error for us -"Error: invalid host, js engine: hermes",

This issue got resolved when we took the release after commenting out the Reactotron code.

[Ajmal0197]

let getEnhancers = () => {
if (process.env.NODE_ENV === 'development') {
const reactotron = require('../../ReactotronConfig').default;
[reactotron.createEnhancer!()];
}
return [];
};

This worked for me thanks:

const getEnhancers = (getDefaultEnhancers) => {
  if (process.env.NODE_ENV === 'development') {
    const reactotron = require('../helpers/ReactotronConfig').default;
    return getDefaultEnhancers().concat(reactotron.createEnhancer());
  }
  return getDefaultEnhancers();
};

// https://redux-toolkit.js.org/usage/usage-guide#use-with-redux-persist
const store = configureStore({
  reducer: persistedReducer,
  middleware: (getDefaultMiddleware) =>
    getDefaultMiddleware({
      serializableCheck: {
        ignoredActions: [FLUSH, REHYDRATE, PAUSE, PERSIST, PURGE, REGISTER], //
      },
    }),
  enhancers: getEnhancers,
});

[vinesh4Real]

Reactotron was causing the issue in release mode, I was able to fix that by commenting out the reactotron code during the release build.

Could you please elaborate on the same issue，thanks @nishadthajudeen001

Only the Release version APP was crashing with this error for us -"Error: invalid host, js engine: hermes",
This issue got resolved when we took the release after commenting out the Reactotron code.

bro, thank you so much. Just delete these few libraries reactotron-react-native reactotron-redux reactotron-redux-saga

I can confirm. Removing reactotron and reactotron related libraries fixed it.

[vinesh4Real]

@Ajmal0197 @tmikov I managed to solve it. Make sure you dont import anything unless you are in development mode.

In our entry file, we were careful to import our reactotron config file (has all the tron config and imports) only if we are in dev mode. Like so,

if (__DEV__) {
  import('./ReactotronConfig').then(() =>
    // eslint-disable-next-line no-console
    console.tron.log('Reactotron Configured'),
  );
}

But we were also using redux enhancers in our redux store declaration, where the import existed regardless of the environment. This is where the error was from. I solved it by importing only after confirming dev environment,

let getEnhancers = () => {
  if (process.env.NODE_ENV === 'development') {
    const reactotron = require('../../ReactotronConfig').default;
    [reactotron.createEnhancer!()];
  }
  return [];
};

const store = configureStore({
  reducer: rootReducer,
  enhancers: getEnhancers(),
});

[Ajmal0197]

@Ajmal0197 that's what I mean, you assigned it but its not called. Add open close brackets getEnhancers()
Se

We can use like this in es6. It's working i have checked properly in release/debug mode

[Ajmal0197]

✅ ✅ ✅
This is solution for now:
infinitered/reactotron#1398 (comment)

[tmikov]

Hi, I am sorry you are having this problem, but unfortunately your report doesn't provide enough information to diagnose it, or even to identify that Hermes is the culprit. Unless you can provide a detailed reproduction with the latest version of Hermes, there is not much we can do.

[karam1ashqar]

same thing happening to me, only in RELEASE, react native app, it happens whenever i try to launch the app, always crashing on launch,

any update your end ? @hacnam0306

"Unhandled JS Exception: Error: invalid host, js engine: hermes"

[hacnam0306]

same thing happening to me, only in RELEASE, react native app, it happens whenever i try to launch the app, always crashing on launch,

any update your end ? @hacnam0306

"Unhandled JS Exception: Error: invalid host, js engine: hermes"

same bro

[Abramovick]

Also been having the same issue, anyone figured out the solution?

[tmikov]

Note that this exception is coming from React Native, not Hermes. AFACT, it is thrown from one of these locations:

• https://github.com/facebook/react-native/blob/d992abc56d02a5a0f025d9252b56c3f7c6ce8945/packages/react-native/React/CoreModules/RCTExceptionsManager.mm#L79
• https://github.com/facebook/react-native/blob/d992abc56d02a5a0f025d9252b56c3f7c6ce8945/packages/react-native/React/CxxModule/RCTCxxUtils.mm#L50

I recommend trying with the latest versions of RN and asking in React Native.

[luanlcampos]

Same problem here using RN 0.73.1. Any news on that issue?

[karam1ashqar]

It was an npm issue for me, I had npm install with --force or legacy peer reps to fix it

[matheusPcruz18]

same thing happening to me, only in RELEASE, react native app, it happens whenever i try to launch the app, always crashing on launch,

any update your end ? @hacnam0306

"Unhandled JS Exception: Error: invalid host, js engine: hermes"

Same issue here, RN 0.71.14. Only on production IOS.

[hacnam0306]

hi guys , i fixed it randomly by remove some useless library , checkout the version of reanimated , clean project by delete yarn.lock & node module and reinstall again <3

[nishadthajudeen001]

hacnam0306 Any further update on this?
can you please share more details on this -?
useless library , checkout the version of reanimated

[liylmn]

Reactotron was causing the issue in release mode, I was able to fix that by commenting out the reactotron code during the release build.

Could you please elaborate on the same issue，thanks @nishadthajudeen001

[Ajmal0197]

Reactotron was causing the issue in release mode, I was able to fix that by commenting out the reactotron code during the release build.

Could you please elaborate on the same issue，thanks @nishadthajudeen001

Only the Release version APP was crashing with this error for us -"Error: invalid host, js engine: hermes",
This issue got resolved when we took the release after commenting out the Reactotron code.

bro, thank you so much. Just delete these few libraries reactotron-react-native reactotron-redux reactotron-redux-saga

I can confirm. Removing reactotron and reactotron related libraries fixed it.

After wasting whole day your soln worked. Any way to keep reactotron also and app crash free

[Ajmal0197]

There is no need for library uninstallation, for now I am manually commenting or uncommenting every reactotron instance during release or debug mode.

[tmikov]

So, this looks like a problem in Reactotron? @Ajmal0197 I see you reported it to Infinite Red, but then closed the issue?

[Ajmal0197]

So, this looks like a problem in Reactotron? @Ajmal0197 I see you reported it to Infinite Red, but then closed the issue?

It's temporarily solved will reopen it. Forgot to reopen.

[lachu97]

SIGABRT: Unhandled JS Exception: Error: invalid host, js engine: hermes
I too getting this same error,that too only in production..I tried it using iphone SE ios version 17+

[vinesh4Real]

@Ajmal0197 Dont you need to call that function?

[Ajmal0197]

@Ajmal0197 Dont you need to call that function?

Already calling see last line. Also u can follow this
infinitered/reactotron#1398

[vinesh4Real]

@Ajmal0197 that's what I mean, you assigned it but its not called. Add open close brackets getEnhancers()

[matheusPcruz18]

I just removed all reactotron code from my project and it worked. Thank you guys.

[nishadthajudeen001]

check this link infinitered/reactotron#1398, latest build 5.0.4 is the culprit for the issue. We will continue to comment out when we take release build still reactotron resolve the issue

[TrustDec]

Change reactotron-react-native in package.json to 5.0.3, instead of ^5.0.3, otherwise the actual version of reactotron-react-native in node_modules is 5.0.4

[sebasgarcia29]

Hello, I remove the dependencies from reactotron-react-native, reactotron-redux, reactotron-redux-saga and reactotron-plugin-zustand works for me, thank you for advices @nishadthajudeen001 !

[OmarUsman777]

I have removed the reactotron configuration from my app, Now it shows blank screen, when i quit the app and start it agian it works fine. But for the first time why is it showing the blank screen?

P.S: This issue is only caused when i try to release the ios app.