A problem was found with the configuration of task ':app:uploadCrashlyticsMappingFileRelease' (type 'UploadMappingFileTask'). - Type 'UploadMappingFileTask' property 'googleServicesResourceRoot' doesn't have a configured value.

Found a fix for me. AS 4.2.1Buld May 10,2021 Gradle Plugin 4.2.1 Gradle Version 7.1 com.google.firebase:firebase-crashlytics-gradle:2.7.0

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, note com.google.gms.google-services is now ABOVE com.google.firebase.crashlytics

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'

When you update to com.google.firebase:firebase-crashlytics-gradle:2.7.0 and sync the changes with them in the wrong order you are given an message stating that is the fix.

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.```

Thanks, that worked. I now have:

plugins {
    ....
    id 'com.google.gms.google-services'
    id 'com.google.firebase.crashlytics'
}