android - Gradle: More than one variant of project :myLib matches the consumer attributes

Question

A library that I wrote myLib uses RemoteMessage from Firebase, the app itself also uses Firebase.

Using gradle 4.7. Also facing this in 4.4.1.

How to fix it?

project.gradle

buildscript {
    
    repositories {
        google()
        jcenter()
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.2'
        classpath 'com.google.gms:google-services:3.3.0'
    }
}

allprojects {
    repositories {
        google()
        jcenter()
        mavenCentral()
        mavenLocal()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

app.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 27
    defaultConfig {
        applicationId "com.test.app"
        minSdkVersion 19
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        multiDexEnabled true
    }

    dexOptions {
        preDexLibraries = false
        jumboMode = false
        javaMaxHeapSize "2048M"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    productFlavors {
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])

    implementation 'com.android.support:appcompat-v7:27.1.1'

    implementation 'com.google.android.gms:play-services-gcm:12.0.1'
    implementation 'com.google.android.gms:play-services:12.0.1'
    implementation 'com.google.firebase:firebase-core:12.0.1'
    implementation 'com.google.firebase:firebase-messaging:12.0.1'
    implementation 'com.google.firebase:firebase-crash:12.0.1'

    implementation project(":myLib")
}

apply plugin: 'com.google.gms.google-services'

myLib.gradle

apply plugin: 'com.android.library'

android {
    compileSdkVersion 27



    defaultConfig {
        minSdkVersion 19
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])

    implementation 'com.android.support:appcompat-v7:27.1.1'

    implementation group: 'com.google.code.gson', name: 'gson', version: '2.8.2'
    implementation 'com.j256.ormlite:ormlite-core:5.0'
    implementation 'com.j256.ormlite:ormlite-android:5.0'

    implementation 'com.google.firebase:firebase-messaging:12.0.1'
}

Error output from testAppmyLib> gradle clean assembleDebug and testAppapp> gradle clean assembleDebug

More than one variant of project :myLib matches the consumer attributes:

• Configuration ':myLib:debugApiElements' variant android-aidl:
  • Found artifactType 'android-aidl' but wasn't required.
  • Required com.android.build.api.attributes.BuildTypeAttr 'debug' and found compatible value 'debug'.
  • Found com.android.build.api.attributes.VariantAttr 'debug' but wasn't required.
  • Required com.android.build.gradle.internal.dependency.AndroidTypeAttr 'Aar' and found compatible value 'Aar'.
  • Required org.gradle.usage 'java-api' and found compatible value 'java-api'.
• Configuration ':myLib:debugApiElements' variant android-classes:
  • Found artifactType 'android-classes' but wasn't required.
  • Required com.android.build.api.attributes.BuildTypeAttr 'debug' and found compatible value 'debug'.
  • Found com.android.build.api.attributes.VariantAttr 'debug' but wasn't required.
  • Required com.android.build.gradle.internal.dependency.AndroidTypeAttr 'Aar' and found compatible value 'Aar'.
  • Required org.gradle.usage 'java-api' and found compatible value 'java-api'.
• Configuration ':myLib:debugApiElements' variant android-manifest:
  • Found artifactType 'android-manifest' but wasn't required.
  • Required com.android.build.api.attributes.BuildTypeAttr 'debug' and found compatible value 'debug'.
  • Found com.android.build.api.attributes.VariantAttr 'debug' but wasn't required.
  • Required com.android.build.gradle.internal.dependency.AndroidTypeAttr 'Aar' and found compatible value 'Aar'.
  • Required org.gradle.usage 'java-api' and found compatible value 'java-api'.
• Configuration ':myLib:debugApiElements' variant android-renderscript:
  • Found artifactType 'android-renderscript' but wasn't required.
  • Required com.android.build.api.attributes.BuildTypeAttr 'debug' and found compatible value 'debug'.
  • Found com.android.build.api.attributes.VariantAttr 'debug' but wasn't required.
  • Required com.android.build.gradle.internal.dependency.AndroidTypeAttr 'Aar' and found compatible value 'Aar'.
  • Required org.gradle.usage 'java-api' and found compatible value 'java-api'.
• Configuration ':myLib:debugApiElements' variant jar:
  • Found artifactType 'jar' but wasn't required.
  • Required com.android.build.api.attributes.BuildTypeAttr 'debug' and found compatible value 'debug'.
  • Found com.android.build.api.attributes.VariantAttr 'debug' but wasn't required.
  • Required com.android.build.gradle.internal.dependency.AndroidTypeAttr 'Aar' and found compatible value 'Aar'.
  • Required org.gradle.usage 'java-api' and found compatible value 'java-api'.

Answer 1

The google-services gradle plugin is made to work with Google Play Services and Firebase 15+, but you're using it with version 12.0.1.

The solution is to either:

• Upgrade your Play Services and Firebase dependencies to version 15+ (note that they have different versions now)
• Cancel your google-services upgrade to 3.3.0 until you upgrade to 15+, that is, downgrading the gradle plugin to version 3.2.1.

EDIT 1: There's a known issue about using google-services 3.3 in multimodule apps. That means downgrading to google-services to 3.2.1 may be your only option until a new version that fixes the bug is released.

EDIT 2: The bug mentioned above has been fixed in the version 4.0.1 of the google-services gradle plugin! (and the version 4.0.2 also fixes an NPE that occurred in some cases)

BTW, you should move to FCM. GCM will stop working in a not too distant future.