Type 'UploadMappingFileTask' property 'googleServicesResourceRoot' doesn't have a configured value

To fix it, the Google Services plugin should be applied before any Firebase plugin in /app/build.gradle.

This produces the error:

apply plugin: 'com.android.application'
apply plugin: 'com.google.firebase.crashlytics'
apply plugin: 'com.google.gms.google-services'
apply plugin: 'com.google.firebase.firebase-perf'

While this does not:

apply plugin: 'com.android.application'
apply plugin: 'com.google.gms.google-services'
apply plugin: 'com.google.firebase.crashlytics'
apply plugin: 'com.google.firebase.firebase-perf

Note that com.google.gms.google-services is ABOVE com.google.firebase.crashlytics.

When you update to com.google.firebase:firebase-crashlytics-gradle:2.7.0 and sync the changes, you are given a message stating that is the fix as follows:

Configure project :app
Crashlytics could not find Google Services plugin task: processReleaseGoogleServices. Make sure com.google.gms.google-services is applied BEFORE com.google.firebase.crashlytics. If you are not using the Google Services plugin, you must explicitly declare `googleServicesResourceRoot` inputs for Crashlytics upload tasks.

Make sure

'com.google.gms.google-services'

is applied before:

'com.google.firebase.crashlytics'

Fixed the error for me.

I also didn't found anything, for now changing to firebase-crashlytics-gradle to 2.6.1 seems ok.