Apple have urged everyone using an iPhone 5 or later to update to iOS 10.3.5 before 3 November if they want to continue using key features like email, web browsing, the app store, and iCloud. The push from Apple for users to update their software comes from the GPS time rollover issue that effects the iPhone 5 and older devices, including the first generation iPad mini.
In order for GPS to know your location, it has to keep track of your date and time. It keeps track of your date by counting the number of weeks that have passed by, then storing that value as a 10-bit figure. Every 20 years that 10-bit number is reset back to zero, also known as rollover. Older devices like the iPhone 5 and first generation iPad mini struggle to deal with this rollover, meaning their GPS capabilities get thrown out-of-whack, which in-turn renders features like email and web browsing useless.
To address the issue, Apple released a support document saying, “starting just before 12:00 a.m. (02:00 am Central African time) UTC on November 3, 2019, iPhone 5 will require an iOS update to maintain accurate GPS location and to continue to use functions that rely on correct date and time including App Store, iCloud, email, and web browsing. This is due to the GPS time rollover issue that began affecting GPS-enabled products from other manufacturers on April 6, 2019. Affected Apple devices are not impacted until just before 12:00 a.m. UTC on November 3, 2019.”
If you fail to update your software by 3 November, wireless updates wont be possible as your device wont be able to connect to a network. However, you will be able to update your device by connecting it to a PC or Mac.
Luckily for Apple, the GPS time rollover issue will only effect a small amount of devices. Apple says that only 9% of all iOS devises are running software earlier than iOS 12.