App Store, iCloud, email, and web browsing will stop working in iPhone 5 if users don’t update to iOS 10.3.4 by 3 November.

Older models of iPhones and mobile-enabled iPads also need to update in order to keep GPS functionality.

An issue with the GPS week number rollover in April has caused the problem.

Because the GPS weekly counter – part of the regularly broadcast date and time – is stored in 10 bits, it has a limit of counting up to 1,023. Therefore, every 1,024 weeks (19.7 years), the GPS week number rolls over to 0, causing problems to devices reliant on GPS for accurate location, date, and time measurements.

iPhone 5s are affected more severely because that model’s services such as email and web browsing won’t function without a correct date and time.

In a support page, Apple warned that failure to update on time will remove the ability to install the update wirelessly.

“It's always a good idea to keep the operating system on your iPhone or iPad updated,” Apple said.

“If the update to iPhone 5 is not completed by November 3, 2019, you will be required to back up and restore using a Mac or PC in order to update because over-the-air software updates and iCloud Backup will not work.”

Having to frequently update devices is annoying part of smart phone ownership, not least because updates can suddenly make your device feel obsolete.

But developers need to constantly push patches in order to fix bugs and security flaws.

Apple recently released its latest round of updates that address security concerns in operating systems across its suite of products.

The iOS updates address vulnerabilities from over a dozen CVEs that opened the potential for attacks like “[forcing] a user onto a malicious wi-fi network during device setup” and “[executing] arbitrary code with kernel privileges”.

Last month, Apple patched out a zero-day vulnerability that had been used to target iPhones for covert mass surveillance operations.