Google不支援通過SDK的更新來更新support庫，需要通過maven倉庫來下載支援庫。

解決方法：

allprojects {
    repositories {
        maven { url 'https://dl.google.com/dl/android/maven2' }
        jcenter()
        maven { url "https://jitpack.io" }
        maven { url 'http://oss.jfrog.org/artifactory/oss-snapshot-local/' }
        google()
    }
}
 

app: build.gradle

dependencies {implementation "com.android.support:support-core-utils:27.0.2"}