No implementation found for void com.unity3d.player.UnityPlayer.nativeRestartActivityIndicator()

If you export the unity project in the build.gradle, you need to add this sentence to your android project app.gradle:

defaultConfig {
    ndk {
        abiFilters 'armeabi-v7a', 'x86'
    }
}

Try enabling ARM64:

1. Update unity to 2018.3
2. In android player settings change "scripting backend" to IL2CPP.
3. In android player settings mark ARM64 checkbox as selected.