Pokémon GO version 0.427.0 is now rolling out for iOS and Android, giving Trainers the latest update to Niantic’s mobile game. The new version follows 0.425.1 and appears to focus primarily on routine bug fixes and performance improvements rather than introducing a major new gameplay feature, with the iOS App Store now listing 0.427.0 as the latest release.
Source: Official Pokémon GO support
Nintendo & Pokémon Blog 