For those who are still holding on to their old iPhone and iPad devices from 7 years ago, Apple has acknowledged an issue which may cause inaccurate GPS, time and date starting 3rd November. This is due to GPS week number rollover which had affected many GPS devices on 6th April 2019.
According to Apple, their iPhone and iPad models manufactured in 2012 and earlier will require an iOS update to main accurate GPS location. This fix is available for the following models and you are urged to update to the latest iOS version over-the-air (OTA) before 3rd November 2019:
iPad (4th gen) WiFi + Cellular
iPad mini (1st generation) WiFi + Cellular
iPad 2 WiFi + Cellular (CDMA model only)
iPad (3rd generation) WiFi + Cellular
Devices that are not fixed will have issues getting the correct GPS position and it may fail to show the correct date and time. This will affect some functions such as syncing to iCloud and fetching email. If you don’t update by 3rd November, the only workaround is to restore via iTunes or Finder via USB.
For older devices, you’re probably out of luck. The last software update for iPhone 4 is iOS 7.1.2 while the iPhone 3Gs is currently stuck with iOS 6.1.6.
Why does this happen?
The GPS week number rollover is caused by the way it calculates time and it takes place every 19.7 years. This is because of the weekly counter is stored in 10-bits which maxes out at 1023. After 1023, the counter goes back to zero but some systems might not be able to handle the rollover. As a result, devices may stop functioning and in some cases, it may move back time by 20 or 40 years.
The first GPS week number rollover occurred on the 21st August 1999 and exactly 19.7 years later, it happened again on 6th April 2019. Newer GPS systems have switched to a 13-bit field for the week number which means you’ll only need to worry about the next rollover in 157 years.
The rollover had affected other devices earlier this year and it has caused flight delays due to incorrect date displayed for some planes. Apple is likely to have restarted their week numbers at a later time which explains why they are experiencing the rollover 7 months later.
You can learn more about the GPS week number rollover in the video below: