React native Android SyntaxError: Attempted to redefine property 'key'

Question

I get the following error on Emulators (tested Genymotion and google Stock Emulator) and on a physical device (Samsung S4) after running react-native run-android

Answer 1

I had the same error but with a different keyword

In my case the keyword was declared twice in my css styles properties.

let styles = StyleSheet.create({
    keyword:{}, 
    keyword:{}
});

No crash or warning on iOS but causing a crash on Android.

Answer 2

The problem was: key was defined twice in a view somewhere, i.e. something like

<View key={index} key={other} ... />

So just remove one of the key properties.

Intermediate step to find the solution:

At first, when pressing Start Chrome Debugging in the React Native Menu, the app will run again, but the error will be shown in the console of the corresponding browser tab. Then it shows a bit better error message.

Strangely this error doesn't occur on iOS.

Answer 3

Encountered the same error on v0.49. Spent a lot of time and finally found that there are duplicates in my css declaration:

logo: {
    flex:.3,
    height: 120, 
    marginBottom: 10,
},

logo: {
    ...styText,
    marginTop: 10
},

just removed the second declaration fixed the error.