What to Do Before You Install iOS 27
iOS 27 arrives on 14 September. The 20 minutes before you tap Install decide whether the update is one you can undo — and the backup that matters is not the one in iCloud.
Kusiima
Latest updates about technology, design and the way we work.
Apple releases iOS 27 on 14 September. The update takes one tap and about half an hour. Going back afterwards is much harder — which is why the 20 minutes beforehand are worth spending.
Make the backup that can undo it
Once your iPhone is running iOS 27, every new backup it makes is an iOS 27 backup — and those will not load back onto iOS 26. If you change your mind next week, only a backup made before you updated can take you back. You cannot make one later.
An iCloud backup keeps your recent data safe and takes a minute: Settings → your name → iCloud → iCloud Backup → Back Up Now. But it will not take you back to iOS 26. For that you need one on a computer, archived so it cannot be overwritten.
On a Mac that is Finder → your iPhone → General, tick “Encrypt local backup”, then Back Up Now — followed by Manage Backups → right-click → Archive, which is the step that stops the next backup replacing it. Keep the encryption password somewhere safe, because Apple cannot reset it. On Windows there is no Archive button at all, so the folder has to be copied by hand.
The full steps for both are here. With no computer at all, you have no way back — so wait for iOS 27.1 rather than updating on the 14th September.
Check what you will actually get
iOS 27 runs on the iPhone 11 and anything newer, plus the iPhone SE (2nd and 3rd generation). But running it and getting all of it are different things. The new Siri needs an iPhone 15 Pro or newer. On an iPhone 12 you get a new Safari, new photo editing and changes to Wallet and Messages — not the Siri everyone is writing about.
Free up the space yourself
If storage is tight, iOS offers to remove apps and put them back afterwards. It usually works, but it chooses for you, and an app that has left the App Store will not come back.
Settings → General → iPhone Storage shows what is taking the room. Photos and video are almost always the answer.
Sort your login codes out first
Banking apps, VPNs and authenticator apps are where trouble turns up every year. Authenticators are the one to watch: if your codes exist only on that phone and something goes wrong, you are locked out of the accounts you would need to fix it. Check the app syncs to the cloud, or save its recovery codes somewhere that is not the phone.
There is no rush
iOS 27.1 will follow within a few weeks and fix whatever the beta missed. Waiting costs nothing. Updating on the morning of a flight or a deadline can cost a great deal.
Pick a quiet hour, plug in, and make that backup first.
