Maintenance for the week of October 12:
• PC/Mac: NA and EU megaservers for maintenance – October 12, 6:00AM EDT (10:00 UTC) – 8:00AM EDT (12:00 UTC)
• Xbox One: NA and EU megaservers for maintenance – October 14, 6:00AM EDT (10:00 UTC) – 9:00AM EDT (13:00 UTC)
• PlayStation®4: NA and EU megaservers for maintenance – October 14, 6:00AM EDT (10:00 UTC) – 9:00AM EDT (13:00 UTC)
I had an unresponsive NPC for a quest. Relogging fixed that. If this is a quest NPC, drop the quest & retake it to see if that fixes your error. I have not had an unknown error since Early Access, so I am not sure if the two are related.