I have exactly the same issue after buying and downloading the HS expansion yesterday. Played ARR for three weeks prior to this with no issues.

I tried all the above, plus from info I found on this forum deleting all traces off FF14 from PS4 and defrag PS4..reinstalling the game didn't work at all. Same error.

Please help, because I'm enjoying the game and now can't play it after spending another £50 on it.