If you try to start the project on Android Smartphone with run or debug.
Then the dialog window: Edit Configuration opens, but you do not know what you should change.
Error: Gradle project sync failed. Please fix your project and try again.
Error:Execution failed for task ':app:preDebugAndroidTestBuild'.
> Conflict with dependency 'com.android.support:support-annotations' in project ':app'. Resolved versions for app (26.1.0) and test app (27.1.1) differ. See https://d.android.com/r/tools/test-apk-dependency-conflicts.html for details.
You just have to go to Android Studion-> Menu-> Make Project Ctrl + F9
Or make module app