- Not enough available storage space on your device
- Downloading the update takes a long time
- Unable to reach the update server
- The update doesn't complete
If there's not enough space to update
If there isn't enough space to download and install an update, iOS will try to make space. It will remove only app data that it can download again and doesn't remove or relocate any of your data. If your device still doesn't have enough space, you can use iTunes to update your device.
If you can't connect to iTunes, you can make room for the update by removing content on your device that you don't use.
- To remove content in iOS 10: Go to Settings > General > Storage & iCloud Usage and tap Manage Storage.
- To remove content in iOS 11: Go to Settings > General > iPhone Storage.
Learn more about the space your apps and content use.
If the download takes a long time
You need an Internet connection to update iOS. The time it takes to download the update varies according to the size of the update and your Internet speed. You can use your device normally while downloading the iOS update, and iOS will notify you when you can install it. To improve the speed of the download, avoid downloading other content or use a Wi-Fi network if you can.
If you can’t reach the update server or can’t verify the update
If you try to update the iOS on your device, you might see one of these messages:
"Unable to Check for Update. An error occurred checking for a software update."
"Unable to Verify Update. iOS failed verification because you are no longer connected to the Internet."
If the update doesn't complete
When you're updating over the air, keep your device connected to a power source. If your device runs out of power, connect it to a power source and turn on the device to let the update or restore complete.
Remove and download the iOS update again
If you still can't install the latest version of iOS, try downloading the update again:
- Go to Settings > General > iPhone Storage.
- Find the iOS update in the list of apps.
- Tap the iOS update, then tap Delete Update.
- Go to Settings > General > Software Update and download the latest iOS update.
If you don’t see the update in the list of apps or if the issue happens again, you need to update your device with iTunes.