Facebook made a small fumble today by logging out all iPhone users. You probably received an error message while opening the iOS app. But this is now ancient history.
“We know that some people are currently having difficulty accessing Facebook. We believe this is due to a change in configuration and we are working to get things back to normal as soon as possible “Facebook told Engadget. The problem has been effectively fixed.
The real problem is with users who have two-step verification in their account. Facebook is sending an SMS verification code to authorize the connection and it has taken a long time to arrive. This is due to the high demand for connections. But tonight everything is good. By the way, it is advisable to prefer a verification code with a dedicated application (Google Authenticator, Auti, etc.) instead of SMS.
If you are signed out of Facebook on your iPhone today, simply tap on your photo to re-access your account. If that doesn’t work, enter your username and password. And if it really gets stuck, remove the app and download it again from the App Store.