Niantic has just pushed out Pokemon Go update 0.91.2 (Android) and 1.61.2 (iOS) just a week after it has previously updated the game. This time however, don’t expect any feature enhancement as the update will be focusing on bug fixes.
In any case, you should head to the Google Play Store or iOS AppStore to update the game.
Trainers, Pokémon GO is being updated to version 0.91.2 for Android and 1.61.2 for iOS to implement bug fixes.
— Pokémon GO (@PokemonGoApp) February 13, 2018