Fabric Debug Craslytic Reports : Signup, build Id missing, apply plugin : io.fabric

This also happens if you set ext.enableCrashlytics = false for a build variant but still try to call Fabric.with(context, Crashlytics()) in your app initialization code. ext.enableCrashlytics = false disables the build plugin (an optimization I made to make my debug builds faster) but then of course the build ID will be missing.

I managed to get this fixed without adding android.debug.obsoleteApi=true in gradle.properties.

I basically connected 3 flavors to different Firebase projects using proper flavor configuration and the provided google-services.json file.

What your gradle file is missing comparing it to mine is this:

dependencies {
    classpath 'com.android.tools.build:gradle:3.2.1'

    // NOTE: Do not place your application dependencies here; they belong
    // in the individual module build.gradle files
    classpath "com.google.gms:google-services:$google_services_version" // google-services plugin

    classpath "io.fabric.tools:gradle:$fabric_tools_version"

}

apply plugin: "io.fabric"

And finally: implementation "com.google.firebase:firebase-crash:16.2.1"

I know Fabric is going to shut down this year, but by running the apps this way, they connected to the Firebase console with no problem whatsoever.

Regarding the flavor configuration, I downloaded three different json files (I have 3 flavors) and added them in the root directory of each flavor. For example:

flavor1:
assets
java
res
AndroidManifest
google-services.json (for flavor1)

flavor2:
assets
java
res
AndroidManifest
google-services.json (for flavor2)

And that's it. Hope this helps someone.

EDIT
So, as you guys may already know, Fabric is shutting down and Firebase Crashlytics is ready, making this answer deprecated.
Please check here so you can successfully update your app and avoid weird behaviors.

Today I migrated from Fabric Crashlytics to Firebase Crashlytics and encountered a fatal error that didn't keep me going. What I did was this: In app-> build.gradle:

apply plugin: 'io.fabric'
dependencies {
 implementation "com.google.firebase:firebase-core:17.2.0"
// Add dependency
implementation 'com.crashlytics.sdk.android:crashlytics:2.10.1'
}

In general build.gradle:

buildscript {

repositories {

    maven {
        url 'https://maven.fabric.io/public'
    }
}
dependencies {
    classpath 'io.fabric.tools:gradle:1.31.2'  // Crashlytics plugin
}

And of course download the json file from Firebase and insert it in the app folder.

After completing these simple steps, I received this error when I started the application

The Crashlytics build ID is missing. This occurs when Crashlytics tooling is absent from your app's build configuration. Please review Crashlytics onboarding instructions and ensure you have a valid Crashlytics account.

I went to check that there wasn't any code that could call up old Fabric methods, and in fact I discovered that in app-> build.gradle I had this:

buildTypes {

    debug {
        minifyEnabled false
        debuggable true
        **ext.enableCrashlytics = false**
        ext.alwaysUpdateBuildId = false
    }    
}

ext.enableCrashlytics = false certainly it was a method that referred to the old Fabric, so I removed this line and everything worked perfectly! I hope to help someone with this