🛠️ (iOS) iOS build fails: 'React/RCTMessageThread.h' file not found when building VisionCameraWorklets (when using react-native-vision-camera-worklets)

[Khaoula-Ghalimi]

Prerequisites

• I have read and followed every applicable step in the Nitro Modules Troubleshooting guide.
• I have read the VisionCamera Troubleshooting guide and Installation guide.
• I did a clean build — deleted node_modules, ios/Pods, ios/build, and Xcode's DerivedData, then reinstalled.
• I searched existing build-error issues and found nothing matching.

Full build error output

Executing react-native-vision-camera Pods/VisionCamera » Copy generated compatibility header
› Packaging expo-dev-launcher Pods/expo-dev-launcher » libexpo-dev-launcher.a

❌  (ios/Pods/Headers/Public/RNWorklets/worklets/apple/WorkletsMessageThread.h:4:9)

  2 | 
  3 | #import <Foundation/Foundation.h>
> 4 | #import <React/RCTMessageThread.h>
    |         ^ 'React/RCTMessageThread.h' file not found
  5 | 
  6 | namespace facebook {
  7 | namespace react {

❌  (node_modules/react-native-vision-camera-worklets/cpp/JSIConverter+AsyncQueue.hpp:12:10)

  10 | #include <jsi/jsi.h>
  11 | #if __has_include(<worklets/RunLoop/AsyncQueue.h>)
> 12 | #include <worklets/RunLoop/AsyncQueue.h>
     |          ^ could not build module 'RNWorklets'
  13 | #elif __has_include(<RNWorklets/worklets/RunLoop/AsyncQueue.h>)
  14 | #include <RNWorklets/worklets/RunLoop/AsyncQueue.h>
  15 | #else

❌  (ios/Pods/Headers/Public/RNWorklets/worklets/apple/WorkletsMessageThread.h:4:9)

  2 | 
  3 | #import <Foundation/Foundation.h>
> 4 | #import <React/RCTMessageThread.h>
    |         ^ 'React/RCTMessageThread.h' file not found
  5 | 
  6 | namespace facebook {
  7 | namespace react {

❌  (node_modules/react-native-vision-camera-worklets/cpp/JSIConverter+AsyncQueue.hpp:12:10)

  10 | #include <jsi/jsi.h>
  11 | #if __has_include(<worklets/RunLoop/AsyncQueue.h>)
> 12 | #include <worklets/RunLoop/AsyncQueue.h>
     |          ^ could not build module 'RNWorklets'
  13 | #elif __has_include(<RNWorklets/worklets/RunLoop/AsyncQueue.h>)
  14 | #include <RNWorklets/worklets/RunLoop/AsyncQueue.h>
  15 | #else
› Compiling expo-dev-launcher Pods/expo-dev-launcher » EXDevLauncherUpdatesHelper.m
› Compiling expo-dev-launcher Pods/expo-dev-launcher » EXDevLauncherRCTDevSettings.m
› Compiling expo-dev-launcher Pods/expo-dev-launcher » EXDevLauncherDeferredRCTRootView.m
› Compiling expo-dev-launcher Pods/expo-dev-launcher » expo-dev-launcher-dummy.m
› Compiling expo-dev-launcher Pods/expo-dev-launcher » EXDevLauncherRCTBridge.m
› Compiling expo-dev-launcher Pods/expo-dev-launcher » EXDevLauncherDevMenuExtensions.m
› Compiling expo-dev-launcher Pods/expo-dev-launcher » EXDevLauncherRedBox.m
› Compiling expo-dev-launcher Pods/expo-dev-launcher » EXDevLauncherManifestParser.m
› Compiling expo-dev-launcher Pods/expo-dev-launcher » EXDevLauncher.m
› Compiling expo-dev-launcher Pods/expo-dev-launcher » EXDevLauncherController.m

⚠️  (../../../../Public/React-Core/React/RCTEventDispatcherProtocol.h:131:12)

@interface RCTBridge (RCTEventDispatcher)
           ^ duplicate definition of category 'RCTEventDispatcher' on interface 'RCTBridge' [-Wobjc-duplicate-category-definition]
› Packaging expo-dev-launcher Pods/expo-dev-launcher » libexpo-dev-launcher.a
› Executing expo-dev-launcher Pods/expo-dev-launcher » Copy generated compatibility header
    Run script build phase '[CP-User] [Hermes] Replace Hermes for the right configuration, if needed' will be run during every build because it does not specify any outputs. To address this issue, either add output dependencies to the script phase, or configure it to run in every build by unchecking "Based on dependency analysis" in the script phase. (in target 'hermes-engine' from project 'Pods')
▸ ** BUILD FAILED **
▸ The following build commands failed:
▸ 	SwiftCompile normal arm64 /Users/expo/workingdir/build/node_modules/react-native-vision-camera-worklets/nitrogen/generated/ios/VisionCameraWorkletsAutolinking.swift (in target 'VisionCameraWorklets' from project 'Pods')
▸ 	SwiftCompile normal arm64 Compiling\ VisionCameraWorkletsAutolinking.swift /Users/expo/workingdir/build/node_modules/react-native-vision-camera-worklets/nitrogen/generated/ios/VisionCameraWorkletsAutolinking.swift (in target 'VisionCameraWorklets' from project 'Pods')
▸ 	SwiftCompile normal x86_64 /Users/expo/workingdir/build/node_modules/react-native-vision-camera-worklets/nitrogen/generated/ios/VisionCameraWorkletsAutolinking.swift (in target 'VisionCameraWorklets' from project 'Pods')
▸ 	Building workspace testcameraframes with scheme testcameraframes and configuration Release
▸ (4 failures)
Exit status: 65
+---------------------------------------+
|           Build environment           |
+-------------+-------------------------+
| xcode_path  | /Applications/Xcode.app |
| gym_version | 2.231.1                 |
| sdk         | iPhoneSimulator26.2.sdk |
+-------------+-------------------------+
Looks like fastlane ran into a build/archive error with your project
It's hard to tell what's causing the error, so we wrote some guides on how
to troubleshoot build and signing issues: https://docs.fastlane.tools/codesigning/getting-started/
Before submitting an issue on GitHub, please follow the guide above and make
sure your project is set up correctly.
fastlane uses `xcodebuild` commands to generate your binary, you can see the
the full commands printed out in yellow in the above log.
Make sure to inspect the output above, as usually you'll find more error information there
[!] Error building the application - see the log above
Error: The "Run fastlane" step failed because of an error in the Xcode build process. We automatically detected following errors in your Xcode build logs:
- 'React/RCTMessageThread.h' file not found
- could not build module 'RNWorklets'
- could not build Objective-C module 'VisionCameraWorklets'
- 'React/RCTMessageThread.h' file not found
- could not build module 'RNWorklets'
- could not build Objective-C module 'VisionCameraWorklets'
Refer to "Xcode Logs" below for additional, more detailed logs.

VisionCamera version

5.0.4

React Native version

0.81.5

React Native architecture

New Architecture (Fabric / bridgeless)

Expo?

Expo 54

Host macOS version

EAS Build (iOS)

Xcode version

EAS Build hosted Xcode environment

iOS Deployment Target

15.1

CocoaPods version

?

Ruby version

?

Build target

Simulator

Package manager

npm

Reproduction repository

https://github.com/Khaoula-Ghalimi/test_camera_frames (5.0.4)
https://github.com/Khaoula-Ghalimi/empty_test_project (5.0.11)

Additional context

So I was in the process of testing camera frames as I do need that for my project with YOLO where I send frame by frame to a nitro module I finished the setup of android which worked perfectly but as I passed to ios I tried firstly to build and see if my nitro module pass but it doesn't even reach it, it shows the react-native-vision-camera-worklets uses a file called React/RCTMessageThread.h which no longer exist in the latest version of react native?
I created this new test project without my nitro module at first it worked with only react-native-vision-camera but when I added react-native-vision-camera-worklets it crashed I tried to clean I deleted my package-lock.json and node_modules but to no avail.
my main project uses 5.0.11 (latest version) as a version of vision camera and its worklets and it still happens. I do have another project that do the same it has 5.0.11 as a version I thought creating a new project can solve things but well nothing works https://github.com/Khaoula-Ghalimi/empty_test_project

Submission

• I pasted the full error output as text (not a screenshot).
• I wrote this report in my own words. I did not paste AI-generated summaries of the error.
• The reproduction repository I linked is public and reproduces the build error on a fresh clone. I understand the issue will be closed without one.

[riteshshukla04]

Can you upgrade your react-native-worklets version to latest and try

[rishik-simplifix]

Can you upgrade your react-native-worklets version to latest and try

Already using latest one for both still same issue

[riteshshukla04]

Maybe create a simple repro of your project with latest version . I can fix then

[NguyenDuyThang]

Any update on it ? I'm also struggling with this when installing react-native-vision-camera-worklets.

For me the error said ...RCTBridge+Inspector.h:11:9: error: 'jsinspector-modern/ReactCdp.h' file not found

It seems that the lib has the problem with useFrameworks flag.

[riteshshukla04]

As I said earlier, Can you just attach a simple RN repro example that can reproduce this issue?

[NguyenDuyThang]

I saw 2 repos attached above

[riteshshukla04]

I saw 2 repos attached above

Both have them have worklets < 0.8.0 which is unsupported, And it has some random math library .

[mrigankdoshy]

Here's how we were able to unblock the issue in our app. Unsure if this is the "correct" fix to upstream tho

Created a patch file react-native-vision-camera-worklets+5.1.0.patch with:

# Workaround for https://github.com/mrousavy/react-native-vision-camera/issues/3997
# iOS build fails: missing 'React/RCTMessageThread.h' pulled in by the worklets module.
# TODO: Re-check on every vision-camera upgrade and drop this patch once the issue is fixed upstream.
diff --git a/VisionCameraWorklets.podspec b/VisionCameraWorklets.podspec
index ed03a68..750e65e 100644
--- a/VisionCameraWorklets.podspec
+++ b/VisionCameraWorklets.podspec
@@ -31,4 +31,26 @@ Pod::Spec.new do |s|
   s.dependency 'React-jsi'
   s.dependency 'React-callinvoker'
   install_modules_dependencies(s)
+
+  # JSIConverter+AsyncQueue.hpp does `#include <worklets/RunLoop/AsyncQueue.h>`,
+  # which makes Clang implicitly rebuild the `worklets` module from THIS target's
+  # compile context (not from RNWorklets's). RNWorklets's public umbrella imports
+  # WorkletsMessageThread.h → `<React/RCTMessageThread.h>` and other headers that
+  # transitively pull in React-Core / Yoga internals. Those live under
+  # `Pods/Headers/Private/*` — paths RNWorklets has on its own search list but
+  # which CocoaPods does NOT propagate to dependents under `use_frameworks! :static`.
+  # Re-add them here so the module rebuild can resolve the full transitive chain.
+  #
+  # NOTE: must MERGE rather than reassign — `add_nitrogen_files(s)` above set
+  # SWIFT_OBJC_INTEROP_MODE / DEFINES_MODULE / SWIFT_INSTALL_OBJC_HEADER on
+  # pod_target_xcconfig, and a bare `s.pod_target_xcconfig = {...}` would wipe
+  # them and break the Swift/Obj-C++ interop the Nitro autolinker requires.
+  existing_xcconfig = s.attributes_hash['pod_target_xcconfig'] || {}
+  s.pod_target_xcconfig = existing_xcconfig.merge({
+    'HEADER_SEARCH_PATHS' => [
+      existing_xcconfig['HEADER_SEARCH_PATHS'] || '$(inherited)',
+      '"$(PODS_ROOT)/Headers/Private/React-Core"',
+      '"$(PODS_ROOT)/Headers/Private/Yoga"',
+    ].join(' '),
+  })
 end

Hope it helps :)

Happy to put up a PR if this seems like the right solution