React-native: Unhandled JS Exception: Unexpected token '{'. import call expects exactly one argument. no stack

[Steffi3rd]

Everything's work fine until I build my project on Xcode to see my app on real device...

Everything is build fine with no errors, yarn start and Xcode Play button (for build)

$ react-native info
info 
  React Native Environment Info:
    System:
      OS: macOS 10.14.1
      CPU: (8) x64 Intel(R) Core(TM) i5-8259U CPU @ 2.30GHz
      Memory: 170.70 MB / 8.00 GB
      Shell: 3.2.57 - /bin/bash
    Binaries:
      Node: 11.10.0 - /usr/local/bin/node
      Yarn: 1.13.0 - /usr/local/bin/yarn
      npm: 6.7.0 - /usr/local/bin/npm
      Watchman: 4.9.0 - /usr/local/bin/watchman
    SDKs:
      iOS SDK:
        Platforms: iOS 12.1, macOS 10.14, tvOS 12.1, watchOS 5.1
    IDEs:
      Xcode: 10.1/10B61 - /usr/bin/xcodebuild
    npmPackages:
      react: 16.8.3 => 16.8.3 
      react-native: 0.59.0 => 0.59.0

[karanjthakkar]

Can you provide a minimal reproducible example for this? That would help us narrow down the issue better.

[Gerlison]

Seems like a error in your code. Can you provide a screenshot of console with Debug JS Remotely?

[turnrye]

Hey @steffi3rd, I suspect that there's actually an issue in your project's code. I think if you look at Metro, you'll see a build-time error.

A few tips:

1. Try resetting all of the caches with:

 watchman watch-del-all && rm -rf $TMPDIR/react-native-packager-cache-* && rm -rf $TMPDIR/metro-bundler-cache-* && rm -rf node_modules/ && npm cache clean --force && npm install && npm start -- --reset-cache

1. Go ahead and upgrade to 0.59.1

Without a repository of your source, it's hard to give specific advice. This seems like an environment issue, but please do follow up with more detail if my pointers above don't help.

[Steffi3rd]

Thanks for your anwser, I did this :

watchman watch-del-all && rm -rf $TMPDIR/react-native-packager-cache-* && rm -rf $TMPDIR/metro-bundler-cache-* && rm -rf node_modules/ && npm cache clean --force && npm install && npm start -- --reset-cache

Now the error has changed but similar.
I don't any details on "Extra Info"

• It works very well on Simulator.
• Metro bundler is build fine
• Xcode project build success

[SourceCipher]

Having the same issue.. Cant see whats causing this nonsense.. Metro running fine, everything compiles.. Upon app launch this error comes up with no indication.. Nothing in the console either..

[MaxBabenko]

Got the same error. Renaming root index.js to index.ios.js did the trick for me. But I'm not sure what is the real issue here

[gianpaj]

Upgrading to these versions seems to have fixed this issue for me on react-native v0.59.8

package.json
```diff
"devDependencies": {

• "@babel/core": "^7.4.4",
• "@babel/runtime": "^7.4.4",
• "@babel/core": "^7.4.5",
• "@babel/runtime": "^7.4.5",
  @@ -101,7 +101,7 @@
• "metro-react-native-babel-preset": "^0.54.0",
• "metro-react-native-babel-preset": "^0.54.1",
  ````

[satya164]

I'm closing this issue since no repro was provided.

[jeffreyhaen]

I'm having the same issue after upgrading to RN 0.59.9. The error message gives basically no clue what's wrong...

[unmec]

I had a similar issue with error Unhandled JS Exception: Unexpected identifier 'App'. import call expects exactly one argument. no stack

So the problem is apparently import App from './App';

I had several code blocks and reminders commented out above it, removing all these comments then the build is successful. So I suggest you to check your import methods.

Also, be careful when comment out code in RN in general, especially within render function. Hope it's helpful.

[unmec]

UPDATE

OK here is the digest of a few good hours spent:

In your index.js, there is something like this:

import { name as appName } from './app.json';
AppRegistry.registerComponent(appName, () => App);

Which import the name from app.json

{
  "name": "yourAppName",
  "displayName": "yourAppName"
}

To get rid of this error, just change index.js to:

AppRegistry.registerComponent('yourAppName', () => App);

and stop importing that json file.

You can keep all your present settings in devDependencies

[ghasemikasra39]

same issue

[wuweijian1997]

Windows 10 - Android

info React Native Environment Info: System: OS: Windows 10 CPU: (8) x64 Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz Memory: 1.19 GB / 7.91 GB Binaries: Node: 10.16.3 - C:\kafka\setting\node\node.EXE Yarn: 1.19.1 - C:\kafka\setting\yarn\bin\yarn.CMD npm: 6.9.0 - C:\kafka\setting\node\npm.CMD
same issue

[ajGingrich]

I fixed this problem by deleting the entire babel.config.js for the time being and letting react-native handle babel

[wonga151]

If this helps anyone I had the same issue and this helped me solve it. https://github.com/facebook/react-native/issues/21530#issuecomment-427577349