Adding on to the voted answer to do some knowledge sharing.
To reiterate, as @Thanhal has posted, the solution and official explanation can be found here: Android build failures No matching variant of com.facebook.react:react-native:0.71.0-rc.0 was found.
The biggest question I needed answer following the error was:
After specifying my react-native version in package.json, why does my project still download another react-native version?
I even used npm install --save-exact
to ensure I am getting the correct version
The error message I was given left me even more confused:
The class is loaded from ~/.gradle/caches/transforms-3/9a8c596b7e1788d5bad7c80991eefff1/transformed/jetified-kotlin-stdlib-1.6.10.jar!/kotlin/Unit.class
e: .../node_modules/expo-modules-core/android/src/main/java/expo/modules/adapters/react/permissions/PermissionsService.kt: (351, 32): Class 'kotlin.Unit' was compiled with an incompatible version of Kotlin. The binary version of its metadata is 1.6.0, expected version is 1.4.1.
Somehow Kotlin became an issue for me as well.
Who / What is asking for the latest react-native?
For my case, the issue here wasn't about the version of react-native my project is using. It was about what my libraries are using.
The react-native team had been shipping a Maven Repository inside the NPM package (node_modules/react-native/android/) up till 0.71.0-rc.0
. Most of the libraries have their build.gradle configured to reference to this directory. This is done through declaring a custom repository in the libraries' build.gradle:
maven {
url "$rootDir/../node_modules/react-native/android"
}
But in the libraries' build.gradle files, more repositories are declared, which may look like this:
repositories {
maven {
url "$rootDir/../node_modules/react-native/android"
}
google()
mavenLocal()
mavenCentral()
}
Then, the dependency for the library is declared as so:
dependencies {
implementation 'com.facebook.react:react-native:+'
}
Because the "+" as version for the react-native dependency, Gradle will take the latest react-native version from the various declared repositories.
Since in the past react-native was shipped with npm package, the latest which Gradle will always take the react-native in node_modules
. However, now that the react-native team is publishing the library to public repositories including MavenCentral, Gradle honours the "+" and take the version on MavenCentral instead.
Why did I get the Kotlin error?
My project uses an older version of react-native and as of version 0.68 react-native started using Kotlin version 1.6.10 (see the change history). So yes, the difference in react-native version would also result in Kotlin error.
+
in the end of this lineimplementation "com.facebook.react:react-native:+"
? inandroid/app/build.gradle
– Stramonium