On its support page, Apple has requested users to update their old iOS devices to the latest version before November 3, 2019. The company says, “Starting just before 12:00 a.m. UTC on November 3, 2019, some iPhone and iPad models introduced in 2012 and earlier will require an iOS update to maintain accurate GPS location and keep the correct date and time. 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.”
It is advisable to update your device as soon as possible as Apple’s support page says that after November 3, 2019, the device might not be able to receive over-the-air software updates.
If you would like to check the software version of your iOS device, you can do so by opening the Settings app, tap General, then tap About. Look for the number next to Software Version. The updated software version number should be 10.3.4 or 9.3.6, depending on your device.
The iPhone 5 and the iPad (4th generation) Wi-Fi + Cellular need to be on iOS 10.3.4. The iPhone 4s, iPad mini (1st generation) Wi-Fi + Cellular, iPad 2 Wi-Fi + Cellular (CDMA models only) and the iPad (3rd generation) Wi-Fi + Cellular need to be on iOS 9.3.6. Apple says that the issue does not affect iPod touch or any iPad models that have Wi-Fi only. It also doesn't affect iOS devices newer than those listed above.