Recent software updates from Apple for their mobile products are not only new iOS 12.4. They also released a new version of firmware to some older devices, but this does not add new features, but to solve some GPS issues. The old device refers here to the classic models such as the iPhone 4s and the original iPad mini. Apple hopes to eliminate the impact of the GPS counting mechanism on older iDevices by upgrades.
Specifically, GPS must use date and time information at normal operation. The way to track the date is to count the week and save the relevant value in 10-bit. However, after about 20 years, the number counted this week will be zero, and this will cause problems for outdated devices that have no built-in coping mechanisms. The last time the value came to zero on April 6 this year, and after Apple updates to older products that could not install the latest iOS, users did not have to worry about it.
After the upgrade, the versions will be included in the iPhone 4s, the original iPad mini, the iPad 2, and the third generation iPad iOS 9.3.6, while the iPhone 5 and the fourth generation iPad become iOS 10.3.4. The effect of zero value values will appear after 3 November this year, so if you plan to use your own product in the future, please complete the update for this day.