Part IV, question 170, page 213
How do you plan a migration from the old architecture?
Question 170 · Senior
The answer
On React Native 0.82 and later there is no opt-in: newArchEnabled=false is ignored, so the plan is about readiness, not a switch. Move first to 0.81 or Expo SDK 54, the last versions that still allow the Legacy Architecture, enable the New Architecture there, and only then upgrade to 0.82. Spend one release on that stepping stone so breakage shows up in isolation.
Production depth
Inventory every native dependency. React Native Directory stores a New Architecture status per library, and npx expo-doctor checks your native dependencies against that data. Know what the interop layer covers: legacy native modules and view components run without migration, but views that define a custom ShadowNode do not. Binaries cannot be recalled, so recovery is a halted rollout plus a fix, with a server flag on risky features.
Common pitfall
Trusting a green expo-doctor run as readiness. It reports metadata, not a test of your app: an untested library may work and a supported one may break on your usage, so run each against the stepping-stone release.
What the interviewer is testing
Inventory from Directory data first, then sequence with known interop limits.
