- If your iPhone is having problems installing an update, it's either due to a lack of RAM or a shaky Wi-Fi connection. It's also a good idea to double-check if updates are set to install automatically.
- Before you begin the update, make sure you have enough of battery life left, or plug in your phone to charge while it is running.
- Go to [Device name] Storage > Settings > General.
- The update can be seen in the app list.
- Then press Delete Update after selecting the update.
- Download the latest update from Settings > General > Software Update.
Read More: How about if iOS 12 won't restart or let you reboot?