Error: You cannot access the app till you log in to www.facebook.com and follow the instructions given

This error is returned by Facebook (as well as Instagram when connecting via authorization through Facebook) when the Facebook user through whom the accounts are connected to the service gets blocked on Facebook. In this case, data collection stops working, as well as the ability to reply from the service.

We don't know the reasons for the block on Facebook's side; more detailed information can be obtained on Facebook.

Therefore, to solve the problem:

• the user who connected the accounts to the service needs to log in to their Facebook account and perform the actions that it requires.
• reauthorize in the account settings using another administrator of the Facebook page.