Apple's biggest iPhone update of the year lands Monday, Sept 14. Nine quick steps get you there without losing a photo, and #6 fixes the "not enough space" wall.
iOS 27 runs on iPhone 11 and every model since, plus iPhone SE (2nd generation) and later. It's the same cut-off as iOS 26, so no iPhone loses support this year.
Apple's major updates usually go live around 10am Pacific, 1pm Eastern. If Software Update shows nothing before then, it isn't broken. Check back after lunch.
The new Siri AI and Apple Intelligence features need an iPhone 15 Pro or any iPhone 16 or later. Older phones still get the redesign and the Photos upgrades.
Go to Settings, tap your name, then iCloud, iCloud Backup, Back Up Now. No iCloud space? Plug into a Mac or PC and back up there instead.
Apple's own advice: connect to power and Wi-Fi before you start. The download is several gigabytes, and a phone that dies mid-install can leave you stuck.
Check Settings, General, iPhone Storage. If the update asks to remove apps for room, tap Continue. iOS removes them temporarily and reinstalls them after.
Open the App Store, tap your profile picture and hit Update All. Developers push iOS 27 fixes this week, so your apps are ready when the new system boots.
Go to Settings, General, Software Update. iOS 27 shows as a separate upgrade below any iOS 26 fix, so tap the iOS 27 option, not the first button you see.
Not ready? iOS 27 is optional. Stay on iOS 26 and keep installing its fixes, and turn off Automatically Install under Software Update, Automatic Updates.
Big updates keep working in the background for a while after install, so a warm iPhone and extra battery drain for a day or two is normal. It settles.