You might be unable to update your iPhone, iPad, or iPod touch wirelessly—or over the air—for one of these reasons.
If there isn't enough space to download and install an update, the software on your device 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 your computer to update your device.
If you can't connect your device to your computer, you can make room for the update by removing content and apps on your device that you don't use. Go to Settings > General > [Device name] Storage.
Learn more about the space your apps and content use.
You need an internet connection to update your device. 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 update, and your device will notify you when you can install it. To improve the speed of the download, avoid downloading other content and use a Wi-Fi network if you can.
If you try to update your device, you might see one of these messages:
Try updating your device again using the same network. If you still see one of these messages, try updating your device using another network or update your device with your computer:
If you're installing the update, the progress bar might appear to move slowly. The time an update takes depends on the size of the update and the number of files on your device.
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.
If you still can't install the latest version of iOS or iPadOS, try downloading the update again: