Beacons.startRangingBeaconsInRegion(region)

[ShellZain]

App crashes when it reaches this line.

Beacons.detectIBeacons();

const identifier = 'iBeacon';
const region = { identifier, UUID };

// Monitor beacons inside the region
Beacons
.startRangingBeaconsInRegion(region)
.then(() => console.log('Beacons monitoring started succesfully'))
.catch(error => console.log(Beacons monitoring not started, error: ${error}));

[joncodeofficial]

The crash on startRangingBeaconsInRegion is almost certainly a New Architecture incompatibility — this library uses the old Bridge and hasn't been updated for RN 0.76+, where the New Architecture is enabled by default.

If you're on RN 0.76 or newer, react-native-beacon-kit is a drop-in replacement built natively on TurboModules + JSI:
→ https://github.com/joncodeofficial/react-native-beacon-kit

The API is similar — startRangingBeaconsInRegion equivalent works without crashes on New Architecture. Also supports Expo.