8.4.0 なのに「updating the version of com.google.android.gms to 8.3.0」

このように怒られ,

Execution failed for task ':app:processDebugGoogleServices'. Please fix the version conflict either by updating the version of the google-services plugin (information about the latest version is available at https://bintray.com/android/android-tools/com.google.gms.google-services/) or updating the version of com.google.android.gms to 8.3.0.

build.gradle を見ると「8.4.0」

apply plugin: 'com.google.gms.google-services'
...
dependencies {
  ...
  compile 'com.google.android.gms:play-services-gcm:8.4.0'
  ...
}

こんな答えだと.

android - Version conflict updating to 8.4.0 - Stack Overflow

...
dependencies {
  ...
  compile 'com.google.android.gms:play-services-gcm:8.4.0'
  ...
}

// 最終行にもってくる
apply plugin: 'com.google.gms.google-services'

 

まとめ

build.gradle (project-top)

...
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.0.0-alpha3'
        classpath 'com.google.gms:google-services:2.0.0-alpha3'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}
...

build.gradle (app-module)

...
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    ...
    compile 'com.google.android.gms:play-services:8.4.0'
    ...
}
apply plugin: 'com.google.gms.google-services'

おつかれさまでした.

google-services_build_gradle_at_master_·_googlesamples_google-services

google-services/build.gradle