'kapt.generateStubs' is not used by the 'kotlin-kapt' plugin
It is completely safe to remove kapt { generateStubs = true }. It was originally used by kapt1, which is deprecated now.
Some docs about kapt:https://kotlinlang.org/docs/reference/kapt.html
You should apply the kotlin-kapt plugin in your build.gradle file and remove the generateStubs = true
apply plugin: 'com.android.application'apply plugin: 'kotlin-android'apply plugin: 'kotlin-android-extensions'apply plugin: 'kotlin-kapt'