Apple quietly updates Apple Watch to only work with iPhones on iOS 18 or later.
If you have an iPhone X or earlier, don’t unpair your Apple Watch from your device because it will stop working. You must have iOS 18 now in order to pair any Apple Watch with your device. iOS 18 is available on iPhone XS or later, and iPhone SE 2nd generation or later.
This was changed recently and Apple released an updated support document. Apple’s previous compatibility chart was more complicated, but it allowed older versions of iOS to work with older Apple Watches. Their chart was not complete, and I made a modified chart to include the iPhone SE models.
Apple’s compatibility chart was dated Nov. 20, 2024, and Apple’s most recent support document is dated Feb. 28, 2025, a Friday.
So on a Friday, right when the news cycle for the week ends, Apple published a support document quietly making it impossible to pair usable Apple Watches with iOS 17 or older devices. I was in the process today of pairing a Series 5 on watchOS 10 with my iPhone SE 1st gen on iOS 15 which was possible according to Apple’s chart, but I could no longer do that and when I clicked on the “Learn More” option, the support document spelled it out bluntly:
To set up and use an Apple Watch, you need iPhone XS or later with iOS 18 or later.
Both the iPhone SE 1st gen and the Series 5 watch are on their latest software revisions, but even then it is not possible.
iOS 18 is the minimum you need now.
It is a bitter sweet ending, since it was quite perplexing to keep track of which watches on which version of watchOS would work with which iPhones on which versions of iOS. Even for a geek like me it was hard to keep it straight. The backwards compatibility was bound to come to an end, and that time is now.
Keep these 4 points in mind:
If you have iOS 18, you can pair any Apple Watch to it.
If you don’t have iOS 18, you cannot pair any Apple Watch to it.
If your Apple Watch is currently paired to an iOS 17 device, it will continue to work, but you might eventually be forced to upgrade to iOS 18 if you have an iPhone XS or later or an iPhone SE 2nd gen or later.
If you have an iPhone X or earlier, unpairing your current Apple Watch will prevent you from re-pairing the device to your iPhone.