Facebook Third Party Connectivity Issues | 5/6/2019
Yesterday afternoon Facebook began experiencing connection issues with third party applications. As a result of this issue you may have notice posts begin to fail with an "unknown error".
Our Product and Development team, as well as our Customer Support and Technical Support teams are monitoring the situation and will update you here as we learn more. As of yesterday evening, the Facebook Support team reported that the issue was resolved, however if you have noticed your posts have failed and need any assistance, please Submit a Ticket to connect with our Support team.
Read more about the issue here: https://developers.facebook.com/support/bugs/1285256981629769/