React Native 0.78 Migration Guide: Lessons from a Real Production App

Why I Migrated

React Native 0.78 brings React 19 support, the new architecture as default, and significant performance improvements. But the migration path is bumpy. Here's every issue I hit and how I fixed it.

Migration Path: 0.76 → 0.77.2 → 0.78

Don't jump versions. I tried going directly from 0.76 to 0.78 and hit a wall of incompatible changes. The safe path:

1. 0.76 → 0.77.2 (bridge version)
2. 0.77.2 → 0.78 (new architecture + React 19)

Use the React Native Upgrade Helper to see file-by-file diffs.

Bug #1: dependencyProvider AppDelegate Issue

After upgrading to 0.77, the iOS build failed with:

No visible @interface for 'RCTAppDelegate' declares the selector 'dependencyProvider'

Fix: The new architecture changed how dependencies are provided. Update your AppDelegate.mm:

// Remove the old dependencyProvider method
// Add the new bundler configuration in didFinishLaunchingWithOptions

Bug #2: cmake pod install Failure on iOS

[!] CDN: trunk URL couldn't be downloaded: cmake

Fix: This is a CocoaPods CDN issue, not a React Native issue. Clean and retry:

cd ios
pod deintegrate
pod cache clean --all
rm -rf Pods Podfile.lock
pod install --repo-update

React 19 Compatibility: Handling propTypes Deprecation

React 19 removes propTypes. If you have libraries using them:

# Find all propTypes usage
grep -r "propTypes" node_modules/ --include="*.js" -l | head -20

For each library, check if there's an updated version. For those that aren't updated, patch them:

npx patch-package library-name

Testing Checklist After Migration

• [ ] App launches on iOS simulator
• [ ] App launches on Android emulator
• [ ] Navigation works (deep links, back button)
• [ ] Push notifications received and handled
• [ ] All native modules functional
• [ ] Hermes enabled and working
• [ ] Release build succeeds
• [ ] E2E tests pass

Final Tips

1. Upgrade one dependency at a time. Don't update React Native AND your navigation library simultaneously.
2. Keep a migration branch. Don't pollute main with migration WIP.
3. Test on real devices. Simulators hide hardware-specific issues.

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