could not find com.android.tools.build.gradle:4.6

Please give more contextual information.

Since I lack these information, I can only make a guess: did you specify the new google() maven repository in your project build.gradle file?

buildscript {
    repositories {
        ...
        google() // this replace https://maven.google.com
        ...
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.0'
    }
}

If you need google() repository in your module(s), you can also add this in your project build.gradle file

allprojects {
    repositories {
        ...
        google()
        ...
    }
}