Crashlytics. Project dev is inactive

It was my bad. This error can occur just if you didn't call 'start()' for Crashlytics. In my case this was off for debug type. Interesting fact: you can On crashlytics for initialize new flavor project on fabric back-end and then switch it off for distribute build for testers if your need it

You can see this error if you have made changes with bundle identifier.

Say you have configured your app with Crashlytics with bundle ID / Package

"com.example.AndroidOne"

and due to some reasons you have to update the bundle ID with

"com.example.AndroidTwo"

and still you are trying to distribute using same old configuration but its fails.

Please do setup / configure the crashlytics again from scratch with new bundleID.

Hope this will help.

From another users response on Stackoverflow:

That means your project hasn't been fully activated on the Fabric backend. After building your app, be sure to run the app as well. This will finish the activation so that you can then distribute your app.

Running the app fixed the problem for me.