com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex – Android Studio 3.0 stable

1. Go to <project>/app/ and open build.gradle file
2. Add the following line to the defaultConfig and dependencies sections

android {
  ...

  defaultConfig {
    ...
    multiDexEnabled true // ADD THIS LINE
  }
}

...

dependencies {
  ...
  implementation 'com.android.support:multidex:1.0.3'  // ADD THIS LINE
}