From 10pm PT to 11pm PT today, Sony will be doing some “routine maintenance and improvements for PlayStation Network.” This will affect the PlayStation 4, PlayStation 3, PlayStation Vita, and website.
If you already have a PSN account, you can sign in, play games, and use most applications during the PSN maintenance. However, you won’t be able to access Account Management, Gaming and Social, PlayStation Store, PlayStation Music, and PlayStation Video during the maintenance.
After giving their usual reminder to activate your PS4 as your primary console (go to Settings > PlayStation Network/Account Management > Activate as Your Primary PS4), Sony says, “We strive to ensure that PlayStation Network services are available at all times, but occasionally we must take PlayStation Network offline to perform essential maintenance and implement feature enhancements. We are working hard to reduce the duration of each maintenance.”
[Source: PlayStation Network]