The given artifact contains a string literal with a package reference ‘android.support.v4.content’ that cannot be safely rewritten. for androidx

New correct answer:

Butterknife 10.0.0 added support for AndroidX.

dependencies {
    implementation 'com.jakewharton:butterknife:10.0.0'
    annotationProcessor 'com.jakewharton:butterknife-compiler:10.0.0'
}

Old answer for Butterknife < 10.0.0:

Try blacklisting butterknife from the jetifier:

gradle.properties file:

android.jetifier.blacklist = butterknife.*\\.jar

You need to be on the 3.3.0-rc1 of the AGP and the 1.3.0 version of the Kotlin Gradle plugin:

buildscript {
    repositories {
        ...
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.3.0-rc01'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.0"
        classpath 'com.jakewharton:butterknife-gradle-plugin:9.0.0-rc2'
    }
}