CE-code mistake 34878-0 relates to a failure in the application / game. To fix it you should do this (in theory), you shall tell us and see if it works;)
Step 1: Close the application, install the latest system update and the game / app, and reboot. (This guess you've already tried)
Step 2: If the error occurs again, back up your saved data, and then go to [Settings]> [Initialize] and select [Initialize PS4].
Let's see if I finish I'm doing a list of all error codes that may arise and I'll post it.
A greeting and counting and we're going mate