NativeUIManager::ApplyLayout assertion fails on secondary window in 0.73.X

[k1mmm]

Problem Description

Assertion fails in NativeUIManager::ApplyLayout on secondary window in 0.73.11 due to rootNode being null. This previously worked fine in 0.72.x.

Microsoft.ReactNative.dll!Microsoft::ReactNative::NativeUIManager::ApplyLayout(__int64 tag, float width, float height) Line 920 C++
Microsoft.ReactNative.dll!Microsoft::ReactNative::NativeUIManager::AddRootView'::2'::<lambda_1>::operator()<winrt::Windows::Foundation::IInspectable const &>(const winrt::Windows::Foundation::IInspectable & __formal, const winrt::Windows::UI::Xaml::SizeChangedEventArgs & args) Line 240 C++
Microsoft.ReactNative.dll!winrt::impl::delegate<winrt::Windows::UI::Xaml::SizeChangedEventHandler,Microsoft::ReactNative::NativeUIManager::AddRootView'::2'::<lambda_1>>::Invoke(void * sender, void * e) Line 4683 C++

Steps To Reproduce

1. Create a secondary window using 'AppWindow'
2. Resize secondary window

Expected Results

No response

CLI version

12.3.6

Environment

System:
  OS: Windows 10 10.0.22631
  CPU: (20) x64 13th Gen Intel(R) Core(TM) i5-13600KF
  Memory: 13.62 GB / 31.82 GB
Binaries:
  Node:
    version: 18.16.1
    path: C:\Program Files\nodejs\node.EXE
  Yarn:
    version: 1.22.19
    path: C:\Program Files (x86)\Yarn\bin\yarn.CMD
  npm:
    version: 9.5.1
    path: C:\Program Files\nodejs\npm.CMD
  Watchman: Not Found
SDKs:
  Android SDK: Not Found
  Windows SDK:
    AllowDevelopmentWithoutDevLicense: Enabled
    AllowAllTrustedApps: Enabled
    Versions:
      - 10.0.18362.0
      - 10.0.19041.0
      - 10.0.22000.0
      - 10.0.22621.0
IDEs:
  Android Studio: Not Found
  Visual Studio:
    - 17.8.34408.163 (Visual Studio Community 2022)
Languages:
  Java: Not Found
  Ruby: Not Found
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 18.2.0
    wanted: 18.2.0
  react-native:
    installed: 0.73.6
    wanted: ^0.73.0
  react-native-windows:
    installed: 0.73.11
    wanted: 0.73.11
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: Not found
  newArchEnabled: Not found
iOS:
  hermesEnabled: Not found
  newArchEnabled: Not found

Target Platform Version

10.0.19041

Target Device(s)

Desktop

Visual Studio Version

Visual Studio 2022

Build Configuration

Debug

Snack, code example, screenshot, or link to a repository

No response

[chrisglein]

Needs someone to dig in and look at the repro. We don't have any simple examples that use multiple windows to start with unfortunately (although that'd be a great item to pair with an investigation here).
@k1mmm if you have a reduced repro in any more detail that'd help jump start this.

You say this asserted. Did it work fine in release?

[k1mmm]

@chrisglein Sorry for the late response, I've set up an example repo for multi-window using AppWindow with react-native-windows@0.73.12, and the error is no longer reproducible, so the error is most likely on my end.

I'm closing this but leaving a link to the repo if you guys or anyone else needs a quick example app with a secondary window sharing the same JS context.

https://github.com/k1mmm/rnwmultiwindow