[UPDATE] According to the PlayStation Network Service Status page, all services are up and running currently, including the PlayStation Store.
If you tried to log into the PlayStation Store earlier today then you might have come across an error message. This error is nothing to do with your network, device, account or anything pertaining to you but was instead a fault with Sony and the company was working to solve the problem.
Oddly enough the PlayStation store was the only affected service that was listed on the PlayStation Network Service Status page You may have some difficulty accessing features and products on the PlayStation Store,” reads an update. “Our engineers are working to resolve the issue as soon as possible, and we thank you for your patience.”
We're aware that some users are having trouble accessing the PSN Store. Thanks for your patience as we investigate: https://t.co/cDmKdG3gXF
— Ask PlayStation (@AskPlayStation) September 13, 2016
This error affects both PlayStation 4 and 3 users and it includes all the basic processes including browsing, searching, purchasing downloading, updating and more.
This issue arrives the same day that the new PlayStation 4 4.00 update was released and there was a new FIFA 17 demo but there is no reason to suspect that either of these were the cause of the problem.