How can I fix this CrashlyticsMissingDependencyException?

I had this commented out in gradle

apply plugin: 'io.fabric'

needed to uncomment it

Or if you don't have it, add it!

I have added the following codes before I actually installed Fabric/Crashlytics:

debug {
    ext.enableCrashlytics = false
}

Removing it before the first run with Crashlytics solved the problem. The problem no longer occurs after the first run.

The only workaround for now, if you really need to publish your app, is to change the dynamic version numbers to static ones:

[...]

classpath 'io.fabric.tools:gradle:1.14.4'

[...]

compile('com.crashlytics.sdk.android:crashlytics:2.2.0@aar') {
        transitive = true
}

[...]

EDIT:

an updated version of the Fabric SDK has been published; you can get it by changing the line to this:

classpath 'io.fabric.tools:gradle:1.26.1'