Short answer: apps crashing after an iOS 27 update usually means third-party apps have not adapted to the new system yet, not that the system itself is broken. The key signal is not the crash but its scope: one or two third-party apps crashing points at those apps, and the fix is updating them; if built-in apps crash frequently too, then it is worth looking at the system side. So the first move is updating your apps from the App Store, not erasing the phone.
Why an update makes apps crash
A major OS release changes the interfaces, permission rules and runtime environment that apps rely on. For a third-party app to work properly on it, the app usually needs to be rebuilt against the new version. Until that adaptation lands, several things can go wrong:
- the app fails to read local data in an old format at launch and exits immediately;
- the app calls a system interface whose behaviour has changed and gets terminated;
- the app needs an additional declaration for a permission under the new system and crashes when it does not get it.
That also explains why some apps on the same phone are fine while others crash — their adaptation schedules differ. Crashes in the first few days after an update are a common phenomenon inside that window, not evidence that your phone is broken.
Four steps, lightest to heaviest
① Update your apps. Open the App Store → tap your picture in the top corner → pull to refresh, and install everything under Available Updates. After a major release, developers typically ship adaptation builds within days to weeks. This fixes most crashes.
② Restart the phone. A normal power off and on is enough. If the crash happens in the first day or two after updating, a restart also clears post-update adaptation work that has not finished. If that does not help, see How to force restart a stuck iPhone.
③ Reinstall that app. Reinstalling clears its cache and local data — and a corrupted third-party app cache is a common cause of crashes, so a reinstall rebuilds a clean environment. In Settings → General → iPhone Storage, opening the app lets you choose Offload App (keeps some documents and data) or Delete App; offloading is gentler. ⚠️ Local data is lost, so confirm anything important is synced or exported first.
④ Update to the latest minor OS version. The first point release after a major version typically cleans up early problems: Settings → General → Software Update.
One app or all apps?
This table tells you which direction to take:
| What you see | More likely cause | Direction |
|---|---|---|
| Only one or two third-party apps crash | Apps not yet adapted | Update, reinstall, report to the developer |
| One app crashes on a specific action every time | A defect in that app's feature | Report it and avoid that action for now |
| Several apps crash at random, built-in ones included | System side or a storage problem | Update the OS, check free space, restart |
| Crashes come with a hot body and a dimming screen | Thermal throttling and limits | Cool it down first — see below |
If you are in the third row, check whether free space has become very tight — with almost no headroom, apps may be unable to read and write temporary files properly, and that connection to crashes is closer than most people assume. See Several GB free but "not enough storage"?.
When it is genuinely a problem
- Built-in apps (Messages, Camera, Settings) crash frequently too, and neither restarting nor updating the OS helps — only then is erasing and restoring, or an Apple check, worth considering;
- the same app crashes on the same action every time — that is the developer's bug, and reporting it beats fiddling with the phone;
- crashes only happen when the body is hot, and stop once it cools — thermal protection is limiting the device, so the fix is cooling; see iPhone heat levels and throttling;
- crashes plus steadily growing storage use — start with iOS 27 System Data huge.
One closing note: crashes do not damage your phone; the app and the system simply have not reached agreement yet. So do not install so-called "repair tools" or cleaning software over one crash — they cannot fix an app's adaptation problem and they bring risk onto your phone instead.