Troubleshooting Native Modules · React Native for Windows + macOS

So you added a new native module or a new method to a module but it isn't working, now what?!

Common Issues

My native method isn't being hit in the VS debugger

A possible reason a method isn't called is a mismatch between the expected and actual types that your method accepts/returns.

To debug into what is rejecting the call, set a breakpoint in facebook::react::CxxNativeModule::invoke. This breakpoint is bound to be hit a lot (every time a call to a native method is made), so we want to make sure we only break when our method of interest is involved.

Right-click on the breakpoint to add a Condition. Suppose the method you are interested in catching is called getString. The conditional breakpoint condition to enter should compare the name of the method to that string: strcmp(method.name._Mypair._Myval2._Bx._Ptr, "getString")==0

`Compile error 'XamlMetaDataProvider': is not a member of 'winrt::MyModuleName'`

Error   C2039   'XamlMetaDataProvider': is not a member of 'winrt::MyModuleName'
Error   C2039   'MyModuleName_XamlTypeInfo': is not a member of 'winrt::MyModuleName'

This can happen if your module includes some XAML markup and you aren't referencing the XAML type information from your C++ app. To fix this, add the following to your C++ app's pch.h file:

#include <winrt/MyModuleName.MyNamespaceName_XamlTypeInfo.h>

(usually MyModuleName and MyNamespaceName will be the same, you can check it in the C# project's properties pane under Root Namespace).

App crashes when trying to load the C# component or instantiate one of its types

Error 0x80131040 "The located assembly’s manifest definition does not match the assembly reference"

C++ apps consuming native modules written in C# need special care. There is a bug in the interop between C# and C++: https://github.com/microsoft/dotnet/issues/1196.

The symptoms are that building the app will work fine but the C++ app will crash at runtime when trying to load the C# module with the error 0x80131040 : The located assembly's manifest definition does not match the assembly reference.

A write-up of the problem can be found here.

As of RNW 0.62, you can enable a ConsumeCSharpModules property in your C++ app to fix the issue:

In your .vcxproj file, set this property within <PropertyGroup Label="ReactNativeWindowsProps">:

<PropertyGroup Label="ReactNativeWindowsProps">
  <ReactNativeWindowsDir Condition="'$(ReactNativeWindowsDir)' == ''">$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), 'node_modules\react-native-windows\package.json'))\node_modules\react-native-windows\</ReactNativeWindowsDir>
+  <ConsumeCSharpModules>true</ConsumeCSharpModules>
</PropertyGroup>

If the above workaround doesn't work, you can try two other (older) workarounds:

Set your C# component's target Windows version to Windows 10 version 1703 (Build 15063) or lower.
Reference the .NET Native NuGet packages in your C++ app:

Right click on the app's .vcxproj file → Manage NuGet Packages.
Search for Microsoft.Net.Native.Compiler, and install it.

Then add the following properties to the .vcxproj file:

<PropertyGroup>
  <UseDotNetNativeToolchain Condition="'$(Configuration)'=='Release'">true</UseDotNetNativeToolchain>
  <DotNetNativeVersion>2.2.3</DotNetNativeVersion>
</PropertyGroup>

Additional resources

For more information and troubleshooting instructions, see the following articles: