No going back: Apple stops signing iOS 13.6.1 code after the release of iOS 13.7

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iOS 13.7 contact tracing feature: Life-saver, or NSA spy tool?
iOS 13.7 upgraded Apple's contact-tracing tools.
Photo: Lewis Wallace/Cult of Mac

Apple has stopped signing iOS 13.6.1, meaning that it is no longer possible to turn back to the earlier version if you have already upgraded to iOS 13.7.

Apple typically stops signing code for previous software versions soon after releasing their successor. That’s because every software update Apple creates is supposed to be faster, more stable, and — most importantly — more secure than the previous version.

It’s therefore in the best interest of users to stop them turning back.

Apple released iOS 13.7 earlier this month. It features improved iCloud Drive folder sharing, and added new Memoji stickers. The biggest update, however, was new capabilities relating to Apple’s COVID-19 Exposure Notifications system.

COVID-19 contact-tracing on iOS 13.7

Apple first introduced Exposure Notifications in iOS 13.5. The initial version required the use of a third-party app developed by a government health agency. iOS 13.7 changed this up with Exposure Notifications Express. This contact-tracing tool means that health agencies do not have to develop standalone apps, which users then need to download. (In some quarters, alleged security concerns about this made people nervous about downloading iOS 13.7.)

iOS 13.6.1, by comparison, was a far less significant upgrade. It sorted out issues such as a thermal management problem, a display glitch, and allowed the system to automatically delete unneeded system data files so as to clear space. Apple released it in the second week of August.

It is likely that iOS 13.7 could be the final version of iOS 13. iOS 14 will likely debut with the new iPhone 12 handsets in October. According to Apple’s most recent developer statistics, released in June, at least 92% of all devices introduced in the last four years currently use iOS 13. It’s likely that number has increased a percentage point or two since then.

Compared to the more fragmented Android ecosystem, it shows how good Apple’s system is at getting people to upgrade to the latest version of its software.