Nowadays we commonly get this type of error in gradle when we use third party library : Manifest merger failed : Attribute application@appComponentFactory value=(android.support.v4.app.CoreComponentFactory) from [com.android.support:support-compat:28.0.0-rc02] AndroidManifest.xml:22:18-91 is also present at [androidx.core:core:1.0.0-rc01] AndroidManifest.xml:22:18-86 value=(androidx.core.app.CoreComponentFactory). Suggestion: add 'tools:replace="android:appComponentFactory"' to <application> element at AndroidManifest.xml:5:5-19:19 to override. we get this types of error when library is updated and providing use of AndroidX but we are using old one. To solve this error we have to migrate our project into AndroidX .if you still don't want to use AndroidX use have to do lots of stuff and also downgrade your googlePlayServices and firebase version. So in this Article we will discuss about what is AndroidX, How to Migrate to AndroidX and when