iOS 27 comes with a nasty surprise for anyone who doesn’t own an Apple Watch Series 10 or later
Your old Apple Watch is now on borrowed time
😟 iOS 27 requires watchOS 27, which is only supported by Apple Watch Series 10, Series 11, Ultra 2, Ultra 3, and the new SE (3rd gen)
👎 Older Apple Watches, including the Series 9 and original Ultra, will lose full compatibility and cannot be re-paired with iPhones running iOS 27
🤖 This change is due to the S10 architecture requirements, which are necessary for new on-device AI features
🤷♂️ Users with older devices will miss out on watchOS 27 improvements and will be unable to pair their watches if they upgrade their phone or reset the device
Apple’s iOS 27 may promise to improve almost every aspect of Mac, iPhone, iPad, and Apple Watch for performance and bug fixes, but the new update hides a major compatibility catch.
Apple didn’t mention it during its WWDC 2026 keynote, but any Apple Watch older than the Series 10 will effectively lose full support once iOS 27 rolls out, as iOS 27 now requires Apple Watches to run watchOS 27.
It means only the Series 10, Series 11, Ultra 2, Ultra 3, and the new Apple Watch SE (3rd gen) will have access to the new Siri AI features, watchOS 27, and more importantly, will pair to an iPhone with iOS 27.
If you have a Series 8, Series 9, SE 2, or even the original Apple Watch Ultra, you won’t be able to re-pair it to your iPhone if you reset the watch, or upgrade to a new phone running iOS 27. You also won’t get any of the improvements watchOS 27 brings.
The issue isn’t cosmetic — it’s structural. iOS 27 now requires watches to run watchOS 27, and Apple has restricted that update to Series 10, Series 11, Ultra 2, Ultra 3, and the new SE (3rd gen).
Why Apple left previous watches behind
Apple’s decision is based on watchOS 27 needing the S10 architecture. Older chips, even the S9 found in the Series 9, don’t meet the performance requirements for Apple’s new on-device AI features.The Series 10 and later models have the all-important neural engine required for Apple’s big AI push.
The move will come as a shock to most, as Apple usually has an admirable track record of supporting older devices. Even iOS 27 is supported as far back as iPhone 11, but unfortunately that isn’t the case for the Apple Watch, which means many users will be forced into an upgrade sooner rather than later.
However, it’s worth mentioning that many of iOS 27’s features, particularly those that rely on AI, will only work on iPhone 15 Pro and newer models.
Beware, then. If you update to iOS 27 and you’re not using an Apple Watch Series 10 or newer, your Apple Watch will essentially become a legacy device overnight. It may keep working for a while, but the moment you need to re‑pair it to your phone, you’re out of luck.
It’s likely, then, that Apple Watch Series 12 will be the first Apple Watch truly designed with Apple Intelligence and on-device AI in mind. Thankfully, we don’t have too long to wait before Apple reveals its next lineup of Apple Watch devices, as a reveal and release is expected to take place in September.
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Adam Vjestica is The Shortcut’s Senior Editor. Formerly TechRadar’s Gaming Hardware Editor, Adam has also worked at Nintendo of Europe as a Content Marketing Editor, where he helped launch the Nintendo Switch. He also runs a retro gaming YouTube channel called Game on, boy! Follow him on X @ItsMrProducts.