Could not find com.google.gms:google-services:4.0.1 [duplicate]

Answer 1

Try adding another maven repository to your project gradle file. For example:

allprojects {
    repositories {
        google()
        jcenter()
        maven { url "https://jitpack.io" }
    }
}

If that doesn't work, adding the OneSignal gradle plugin, also to the project's gradle, might do the trick (as suggested in this answer).

apply plugin: 'com.onesignal.androidsdk.onesignal-gradle-plugin'