React Native Environment Info:
System:
OS: macOS High Sierra 10.13.5
CPU: x64 Intel(R) Core(TM) i7-4770HQ CPU @ 2.20GHz
Memory: 1.34 GB / 16.00 GB
Shell: 3.2.57 - /bin/bash
Binaries:
Node: 8.9.4 - ~/.nvm/versions/node/v8.9.4/bin/node
Yarn: 1.7.0 - /usr/local/bin/yarn
npm: 5.8.0 - ~/.nvm/versions/node/v8.9.4/bin/npm
Watchman: 4.9.0 - /usr/local/bin/watchman
SDKs:
iOS SDK:
Platforms: iOS 11.4, macOS 10.13, tvOS 11.4, watchOS 4.3
Android SDK:
Build Tools: 23.0.1, 25.0.0, 25.0.1, 25.0.2, 25.0.3, 26.0.0, 26.0.1, 26.0.2, 26.0.3, 27.0.0, 27.0.1, 27.0.2, 27.0.3, 28.0.1
API Levels: 21, 23, 24, 25, 26, 27, 28
IDEs:
Android Studio: 3.1 AI-173.4819257
Xcode: 9.4.1/9F2000 - /usr/bin/xcodebuild
npmPackages:
react: 16.4.1 => 16.4.1
react-native: 0.56.0 => 0.56.0
npmGlobalPackages:
react-native-cli: 2.0.1
react-native-create-library: 3.1.2
react-native-extended-cli: 1.0.202
react-native-git-upgrade: 0.2.7
I get error 'cxxreact/ReactMarker.h' file not found while running tvOS
Step 1: Switch schema to tvOS
Step 2: Run

I got the same thing when upgraded to 0.56.0 on a tvOS app. I downgraded to 0.55.4 and it resolved it for now.
I am running into the same issue.
2 days ago, I could still run my app on my iPhone without any issue.
Now getting these kind of error (the one mentioned above is one of them).
I run react-native 0.56 for some time without any issue and haven't changed anything after the last time I had the app run on my iPhone.
What the hack is going on, is xcode or react-native changing my stuff on its own???
oh btw, I do not run iOS-tv, just iOS.
As 0.56.0, I can't compile even a freshly created project for tvOS as well (using XCode Version 9.4.1 (9F2000)).
To make it work, I manually added necessary headers and sources to React project as a temporary fix.
Here are some detailed instructions for people who are not familiar with iOS development or XCode:
First, you should be getting an error as "'cxxreact/ReactMarker.h' file not found". To fix this
cxxreact-tvOS target from the side menu.ReactMarker.h, select it and click Add.JSExecutor.cpp.yoga-tvOS target in the same React project.YGConfig.h to Copy Headers section and YGConfig.cpp to Compile Sources.Project should compile and run now.
The whole community contributes to react-native, and when something is fixed in one place, something becomes broken somewhere else.
Is there any way to prevent those?
Most helpful comment
As 0.56.0, I can't compile even a freshly created project for tvOS as well (using XCode Version 9.4.1 (9F2000)).
To make it work, I manually added necessary headers and sources to React project as a temporary fix.
Here are some detailed instructions for people who are not familiar with iOS development or XCode:
First, you should be getting an error as "'cxxreact/ReactMarker.h' file not found". To fix this
cxxreact-tvOStarget from the side menu.ReactMarker.h, select it and click Add.JSExecutor.cpp.yoga-tvOStarget in the same React project.YGConfig.hto Copy Headers section andYGConfig.cppto Compile Sources.Project should compile and run now.