[android] Error:(9, 5) error: resource android:attr/dialogCornerRadius not found

This Is Because compileSdkVersion , buildToolsVersion and Dependecies implementations are not match You Have to done like this i have 28 library then

compileSdkVersion 28
targetSdkVersion   28
buildToolsVersion  28.0.3
implementation 'com.android.support:design:28.0.0'
implementation 'com.android.support:appcompat-v7:28.0.0'

If we You Use Any where less than 28 this error should occured so please try match library in all.