Discontinued support for Android 4 KitKat
Pokémon GO is ending support for devices running on Android 4 KitKat. Trainers using devices with this operating system will no longer be able to access Pokémon GO starting July 1, 2019. We encourage Trainers on Android 4 to upgrade their operating system for continued access to Pokémon GO.
Who is affected by this change?
Only devices with Android 4 installed are affected by this change. Apple users and Android users on Android 5 or above are not affected and do not need to take any action.
If you are not sure which OS version is installed on your device, you can typically find this information in the device settings. Go to Settings > System > About.
What do I need to do?
If you’re using a device running Android 4, you will need to update to Android 5 or above to continue to access Pokémon GO. For detailed information on how to update to the latest version of Android, please view this support article on the Android Help Center.
Why this change?
Android 4 was initially released in 2013. In the time since the release, there have been some major improvements to the Android operating systems. By removing support for Android 4, we are able to streamline our development process and focus resources on supporting newer operating systems and technologies.
A vast majority of Android users have migrated to Android 5 and above. As players migrate from older operating system versions to newer ones, we periodically update our supported device requirements to focus on the devices our playerbase use.
Source: Official Pokémon GO support page