Still having the same problem anyone come up with a fix? Never too late to post the solution can't find it anywhere on the internet. Pretty sure there are still lots of people with this problem .
I fixed it by deleting all of my billing info and selecting "NO" to being asked for my password before a purchase. Then all I did was add the exact amount of funds I needed to buy the DLC and re-entered all of my billing info and it worked fine.
I tried this changing my time date still nothing and I still can't get into PSN store still says error after I quit it restarts my PS3. I even tried del and reinstalling the store still error redownloading the firmware also still noting I at a lost. Tragic! there goes my P. Plus membership!
I dont know whats wrong, I put in the correct billing information and I tried deleting and reinstalling the ps store, I tried purchasing ghosts online but the same "an error has occurred" keeps popping up, help