Description:
In v91, there is an issue that app crashes frequently when using Facebook login in iOS.
As a temporary solution, if you have linked a login provider other than Facebook (Google, Apple, or Nintendo account), please use that. Once the app is uninstalled and reinstalled, it is possible to return to the app login screen.
If you have not linked a login provider other than Facebook, please wait for the issue to be resolved, or you can link another login provider (Google or Apple) by logging or signing up into Pokémon GO with your Facebook account. If you are not using a Facebook login provider, please wait for the problem to be resolved.
Status:
The issue has been resolved in v91.1. Please update your app in the app store.