If you’re having trouble logging in, it may be temporary, so please try again at a later time.
If the issue persists, there are a few things you can try. First, please make sure you're using the latest version of Tinder.
Try force quitting the app: double tap the Home button, swipe Tinder up to force quit the app, and try opening Tinder again. Make sure that you're signing in with the correct Facebook account in the Facebook app and your phone's iOS settings.
Try force quitting the app: go to “Settings”, find “Apps”, select Tinder, hit “Force quit”, and open Tinder again. If this doesn’t solve the problem, go the phone settings, find “Apps”, select Tinder, choose “Storage”, and hit “Clear data”.
On Tinder for web (Tinder.com):
Make sure that you're signing in with the correct phone number or Facebook profile associated with your Tinder account. You can also try clearing your browser's cache before attempting to log in again.