Spring social AuthorizationException with Facebook

Between 7:30 pm CET and 8:30 pm CET on March 27, my site suddenly reported this error when logging into Facebook:

HTTP Status: 500 (Internal Server Error)

Message: The operation requires authorization, but the API binding was created without authorization.

Exception: org.springframework.social.MissingAuthorizationException

      

        
        
        
      

    

The site / server has been running unchanged since the end of last year. Does anyone know if something was done on that particular day?