Right before the maintenance was scheduled to begin, Ask PlayStation said:
The PSN maintenance scheduled for tonight has been postponed. We’ll let you know when the new date and time has been set. Thank you!
— Ask PlayStation (@AskPlayStation) August 18, 2015
Changing up the timing from their original announcement, Sony will be performing “routine maintenance and improvements for PlayStation Network,” which will last for approximately 90 minutes today, August 18.
Beginning at 12am PT/3am ET/7am GMT, Sony expects the maintenance to end around 1:30am PT/4:30am ET/8:30am GMT.
As they add, “Anyone who already has an account can still sign in to their PlayStation Network profile, play games, and use most applications while this maintenance is carried out.” However, you won’t be able to access Account Management, PlayStation Video, or complete a purchase in the PlayStation Store.
By activating your PlayStation 4 as Primary, you’ll receive the “best experience” while the PSN is undergoing maintenance.
Sony hasn’t given specifics on what exactly they’ll be improving with the maintenance, but it could be prep for PS4 firmware update 3.00, which recently had its potential changes leaked by a beta tester.
For up-to-the-minute details, be sure to check out the PSN Status Page.