I got this error even though the Foreign Key constraint had been deleted from the database and I had re-executed all my EF Template files, had refreshed my Model from the database and had deleted the relevant Navigation propertry from my Model.
Thing is , I had forgotten to physically delete the Association in the Model Designer .edmx file. When I did that and then re-ran my Model Template file all was well.
So I reckon I had only refreshed the secondary (referencing) table in the FK side. Next time I will refresh the primary (referenced) table as well.
That’s all. Get back to what you were doing. The door is the wooden thing in the wall behind you.