React Native Codegen Build Error Fix: New Architecture iOS & Android
React Native Codegen build failed after upgrading to the New Architecture? Fix ReactCodegen, FBReactNativeSpec.h, generateCodegenArtifactsFromSchema, iOS pods, Android Gradle, and unsupported native packages.
On this page
While building a React Native or Expo app, you may suddenly encounter Codegen, TurboModule, Fabric, or New Architecture errors. These errors usually appear after upgrading React Native, updating Expo SDK, installing a native package, or switching to a newer React Native version. Common errors include `React-Codegen.podspec failed`, `FBReactNativeSpec.h file not found`, `generateCodegenArtifactsFromSchema FAILED`, and CMake or JNI build failures on Android.
The Error
What Causes This Error
React Native Codegen generates native files required by TurboModules and Fabric components. During iOS and Android builds, React Native scans your app and native dependencies, then creates platform-specific files. If generated files are stale, pods are outdated, Gradle cache is corrupted, or a native package does not support the New Architecture properly, the build fails before the app can run.
- Stale React Native generated files
- Outdated iOS Pods or Podfile.lock
- Android Gradle cache using old Codegen output
- Unsupported native package
- React Native and native package version mismatch
- Invalid custom TurboModule or Fabric spec
- Old native config files after React Native upgrade
- Trying to disable New Architecture on newer React Native versions
Fix 1: Clean Generated Files and Rebuild
The most common cause is stale generated files. Delete node_modules, iOS pods, Android build folders, and Gradle cache, then reinstall everything from scratch.
Fix 2: Find the Package Causing Codegen Failure
Most Codegen errors are caused by one incompatible native package. Read the build log above the final error and check which package was processed right before Codegen failed.
Fix 3: Update the Broken Native Package
If the same package appears before the failure every time, update it to a version that supports your React Native version and the New Architecture.
Fix 4: Check React Native Version Compatibility
Codegen errors often happen when React Native, Expo SDK, native libraries, CocoaPods, or Gradle versions do not match. A package that worked in an older React Native version may fail after upgrading because newer versions depend more heavily on the New Architecture.
Fix 5: Use Expo-Compatible Package Versions
For Expo projects, avoid installing random latest package versions with plain npm install. Expo expects specific package versions for each SDK. Use Expo commands to check and fix dependency mismatches.
Fix 6: Reinstall iOS Pods
On iOS, Codegen is connected to CocoaPods. If Pods or Podfile.lock are stale, iOS can fail with missing generated headers, React-Codegen errors, or podspec failures.
Fix 7: Clean Android Gradle Build
On Android, Codegen errors often appear as Gradle, CMake, JNI, Java, or Kotlin compilation failures. Cleaning Gradle and Android build folders forces React Native to regenerate fresh native output.
Fix 8: Check New Architecture Settings
Older guides often recommend disabling the New Architecture with newArchEnabled=false or RCT_NEW_ARCH_ENABLED=0. This is no longer a reliable long-term fix in newer React Native versions. Instead, update incompatible packages and clean generated files.
Fix 9: Check Custom TurboModule or Fabric Specs
If your app has custom native modules, your own Codegen spec may be invalid. A wrong jsSrcsDir, unsupported type, wrong native module name, or invalid TypeScript syntax can break the build.
Example TurboModule Spec
Fix 10: Compare Native Config With a Fresh Project
React Native upgrades often require native file changes. If your Podfile, Gradle files, Hermes settings, or New Architecture flags are still from an older React Native version, Codegen may fail even when all dependencies are installed correctly.
Final Working Commands
Expo Fix Commands
Quick Diagnosis Checklist
- Clean generated files first
- Delete Pods and Podfile.lock on iOS
- Clean Gradle and Android build folders
- Check the first real error above the final build failure
- Find the package mentioned before Codegen fails
- Update incompatible native packages
- Run expo-doctor for Expo projects
- Check custom TurboModule or Fabric specs
- Do not rely on newArchEnabled=false as a permanent fix
- Compare native files with a fresh React Native project
Official-Style Error Explanation
React Native New Architecture Codegen errors happen when React Native cannot generate or compile the native files required by TurboModules, Fabric components, or New Architecture-compatible packages. The root cause is usually stale generated files, outdated native packages, mismatched React Native versions, broken iOS pods, old Android Gradle output, or invalid custom native specs. Start by cleaning generated files and reinstalling pods, then identify the package mentioned before the Codegen failure. In modern React Native projects, updating incompatible dependencies is better than trying to disable the New Architecture.
FAQ
Why does React Native Codegen fail after upgrading?
Because newer React Native versions depend more heavily on the New Architecture. If one native package, generated file, pod, Gradle cache, or native config file is outdated, Codegen can fail during the build.
Can I fix this by disabling the New Architecture?
Only on older React Native versions that still support the legacy architecture. On newer versions, disabling the New Architecture may be ignored or may not fix the real issue. Updating incompatible dependencies is the better fix.
Why does iOS fail with React-Codegen or FBReactNativeSpec.h?
iOS depends on CocoaPods and generated headers. If Pods, Podfile.lock, or Xcode DerivedData are stale, iOS may fail even when Android works. Delete Pods, reinstall pods, and clear DerivedData.
Why does Android fail with generateCodegenArtifactsFromSchema?
Android uses Gradle to generate and compile Codegen output. If Gradle cache or generated build folders are stale, the task can fail. Clean android/.gradle, android/build, android/app/build, and run ./gradlew clean.
How do I find the package causing the Codegen error?
Scroll above the final error and look for the last package processed by Codegen. The package mentioned immediately before the failure is usually the incompatible or broken dependency.
Shahmeer Rizwan
Full-Stack Developer