crashlytics developer tools error when building android -gradle project

Had a similar error trying to use Fabric's Twitter Kit

Error:Execution failed for task ':app:fabricCleanupResourcesDevDebug'.> Crashlytics Developer Tools error.

Detailed error

ERROR - Crashlytics Developer Tools error. java.lang.IllegalArgumentException: Crashlytics found an invalid API key: XXXXXXXXX. Check the Crashlytics plugin to make sure that the application has been added successfully! Contact support@fabric.io for assistance.

After login in Fabric, download the AndroidStudio plugin and let it configure everything all worked fine.

(Btw, I really don't like this setup flow)

EDIT: It also can be done without install the AndroidStudio plugin. Follow these instructions from the Fabric site https://fabric.io/downloads/gradle

This is not a solution to the original question, but you can also run into this error another way. If you are following docs for the Gradle Advanced Setup you might have included the following code

debug {    ext.enableCrashlytics = false}

Now if you are testing your application you may have tried to set ext.enableCrashlytics = true instead. Apparently this will cause errors for Crashlytics though and is not a valid value for this variable.

So if you want Crashlytics enabled for debug builds you'll need to comment out this line while you are testing or remove it altogether.

By adding this line to your Application's Manifest inside tag

<meta-data        android:name="io.fabric.ApiKey"        android:value="XXXXXXXXXXXXXXX" />

I resolved this issue