People using older versions of the iPhone may be locked out of several apps on Sunday if they don’t upgrade to the new iOS.

iPhone 5s and other Apple devices released in 2012 and earlier, need to be updated to iOS version number 10.3.4. Without the update, any apps that rely on accurate dates and times, including the App Store, iCloud, email, and web browsing, will not work.

Apple said the issue is with the “GPS time rollover” in GPS-based products, which resets the clock.

Users have until midnight Saturday to upgrade the iOS on their device.

Apple has denied claims that they intentionally shorten the life of their products, or degrade the user experience to drive customer upgrades after many users have been apprehensive to upgrade iPhones with older batteries because of performance issues.