I recently received this app after updating to Crashlytics 3.0 Not sure if it comes from my code or something else. The crash report is untraceable
Here is
It turns out to be bug of the frame work
Here is what I got from the support of Crashlytics
This should be all set if you update to 3.0.10 of the Crashlytics SDK - there was a rare race condition in 3.0.9 that we patched up with the latest version. Open up Fabric.app, update the framework and you'll be good to go :)
The support team of Crashlytics are awesome!