After recent release of new version of Pokemon Go, many iPhone users couldn’t manage to update new version of Pokemon Go with their phones. If you are having similar problem with the application. Pokemon Go has been released a troubleshooting page for you. You will able to learn how to update the application step by step with this troubleshooting page and you can use the new version of the game.
You will need to update the application from AppStore but not through the game. You won’t need to use any third party services or download application from another websites or services for that. You can click on the link above and get more information about updating the application instantly. You can report the situation via iTunes if you are still having trouble with updating the game. This error generally occurs in iOS and iPhone devices. There is not any known error like this for Android phones yet. Good luck!