In a support document published over the weekend, Apple warns that those with the older iPhone will need to update their devices to iOS 10.3.4 by Nov. 3 at 12:00 a.m. UTC (8 p.m. ET/5 p.m. PT on Nov. 2) if they want to keep using them. The issue is tied to the GPS system on the device and maintaining an accurate GPS location.

Apple uses GPS to help with date and time and due to a "GPS time rollover issue," not updating could lead to being disconnected from "functions that rely on correct date and time including App Store, iCloud, email, and web browsing."

The GPS rollover issue occurs once every 19 years and is rooted in how long GPS devices can hold dates. That clock reset in April, causing some older devices that relied on GPS for date and time to need to have their software updated to adjust.

Those still using other 2012 and earlier Apple gear such as a fourth-gen iPad Wi-Fi with Cellular, iPhone 4S and a handful of older iPads will also want to make sure they've updated their software to the latest, respective versions available for their devices.

The company says other, more recent iPhones and cellular iPads are not affected (Wi-Fi-only iPads don't have GPS).

You can update your iPhone or iPad wirelessly by going to Settings, tapping General and then Software Update. If you haven't updated before the November date you will need to manually plug into a computer and update through a Mac or PC to continue using your devices.