Google Fabric: UiAutomation not connected

It seems like nothing to worry about (don't rely on accepted answer and don't remove your tests) because crashes have been reported on creating pre-launch report for google play store where some UI automation tests were executed. If you track devices on which this error has occurred then you'll see that all paths lead to pre-launch report.

You can find out more about pre-launch report here

It seems that this crash is related to UI testing in your app. If you don't have any UI testing and there are only default settings which added automatically during creating the project, you should remove from your build.gradle the line testInstrumentationRunner in defaultConfig

  defaultConfig {   ....   testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"} 

and androidTestCompile, testCompile in dependencies

dependencies {androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {    exclude group: 'com.android.support', module: 'support-annotations'})testCompile 'junit:junit:4.12'...

One thing is sure: you have an issue on UI. In most cases this occurs when you show a progress dialog that keeps being displayed for too much time. In this case the Google crawler goes in timeout and raises an exception.My advice is: be sure to not block UI with infinite dialogs.