Try freeing up some space on your iPhone 7 to rule out the possibility of not having enough capacity to download and install an update. In this circumstance, iOS will often try to free up space by eliminating only app data that it can redownload. However, you can help make room for the upgrade by deleting unnecessary files from your device. Here's how to get rid of something with iOS 11:
- Go to the Settings tab.
- Select General.
- Select iPhone Storage from the menu.
- Go to Settings-> General-> Storage & iCloud Usage-> Manage Storage if your iPhone is running iOS 10.
Examine the details of the content and delete any items that are no longer helpful. After you've freed up space on your iPhone 7, try to get the latest iOS update again and see if it works this time.
