Sony's recent PlayStation 4 firmware update v9.0 has quietly solved an issue with the console's internal CMOS battery.
This battery powers an internal clock the console uses to check eligibility for game ownership. Without the battery - such as when it naturally drains - both physical and digital games are left unplayable without connecting online.
Reports this week suggested the problem had been fixed in the v9.0 software update, even though it is not mentioned in Sony's official patch notes. Our Digital Foundry team has since been able to corroborate this and confirm the problem is indeed now solved.
The issue first came to light back in April, when it was flagged by Does it play?, a Twitter account devoted to game accessibility and preservation. Fan research found the issue also affected Trophies, which also require a date check prior to unlocking. (These now unlock, albeit with their date field blank.)
Of course, most PS4s have not (yet) experienced a CMOS battery death. Even if (when) yours does drain, it's fair to say most PS4s are connected to the internet so an online check can still be performed.
Still, fans said the way this worked needed to change to avoid future problems for PS4 owners who play offline. There's also the issue of game preservation and the ability to play games long-term even if PlayStation Network is experiencing issues or one day is taken down.
In other welcome changes, Sony's new system update for PS5 has finally added the ability to upgrade the console's SSD expansion, among other things.