About PS3 System Software Update 4.31:
There will not be PlayStation Network maintenance during this time; online play and access to apps will not be affected during the release of this update.
This is not a mandatory update. However, we suggest you keep your systems updated with the latest firmware, as these updates further improve overall system stability and help provide you with the best online entertainment experience possible.
To update to v.4.31, select Settings from your Xross Media Bar (XMB) *> System Update > Update via Internet and then follow the on-screen instructions.