I had the error CE-34878-0 appear when loading my Save the other night. Deleted and the re-installed the game and then updated to the latest version. When loading the old Save File the problem was still there. I then turned off Auto Upload of Save Files to PS Plus Account. Deleted the Save File on PS4 and started a new game with no problems at all. I then quit out and uploaded the old Save File from PS Plus and started/loaded the game which crashed on loading at the same point. That confirmed to me that the Error Code is related to corrupted Save File Data.
The good news for me at least I get to start the game from scratch and streamline my approach to the game - just as well the wife and I LOVE pouring the hours into this game!!