No virtual method zzbqo()Z in class Lcom/google/firebase/FirebaseApp; or its super classes (declaration of 'com.google.firebase.FirebaseApp'

Upgrade the following:

implementation 'com.google.firebase:firebase-database:11.8.0'
implementation 'com.google.firebase:firebase-auth:11.8.0'
implementation 'com.firebaseui:firebase-ui-auth:4.0.0'

to this:

implementation 'com.google.firebase:firebase-auth:16.0.2'
implementation 'com.google.firebase:firebase-database:16.0.1'
implementation 'com.firebaseui:firebase-ui-auth:4.1.0'

also add:

implementation 'com.google.firebase:firebase-core:16.0.1'

In the top level gradle file upgrade the google-service plugin:

classpath 'com.google.gms:google-services:4.0.1'

https://firebase.google.com/support/release-notes/android

The firebaseui needs to be compatible with the firebase versions, check the following link for more information:

https://github.com/firebase/FirebaseUI-Android/blob/master/README.md#dependencies