The situation

You are a lead mobile engineer at a mid‑size SaaS company. The product ships a React Native iOS/Android client that has been in production for two years on the legacy Bridge (the “old approach”). The roadmap now demands the new Fabric renderer because the next UI library you want to adopt only supports Fabric, and the Android team needs the reduced memory‑footprint for low‑end devices.

You schedule a feature flag rollout for the next sprint, but the release calendar already has a hard freeze for the holiday season. When you enable Fabric in a dev build you see the following error on Android:

java.lang.IllegalStateException: UIManager is not set.…