In general, iPhone should automatically download and install updates. If this is not happening, you can find below the steps to fix the problem of iPhone Not Updating.
iPhone is Not Updating
In case of major and well publicized iOS updates, millions of iPhone users will be trying to download updates on their iPhone, which usually results in Apple severs becoming overloaded.
Hence, in case of major iOS updates it may take a while for your iPhone to be able to connect to Apple Servers and download the Updates.
Hence, try updating your device on the second day of a major iOS update. If you are still unable to install updates, it is likely that some other problem is preventing your iPhone from installing updates.
1. Reboot iPhone
Rebooting helps in terminating stuck programs and processes, which might be preventing your iPhone from installing Updates.
Go to Settings > General > scroll down and tap on Shut Down. On the next screen, use the Slider to Power OFF iPhone.
Wait for 30 seconds and press the Power button to Restart iPhone.
After iPhone restarts, go to Settings > General > Software Update and allow iPhone to search for Updates.
If an Update is available, tap on Download & Install to install the update on your iPhone.
2. Check Storage Space
iOS updates can range anywhere from 0.5 to 1.5 GB or more in size. Hence, make sure that there is enough storage space available on your iPhone.
Go to Settings > General > iPhone Storage > On the next screen, you will be able to see the amount of storage space used and available on your device.
If you have about 1.6 GB storage available, lack of storage space is unlikely to be the reason for iPhone Not Updating or installing Updates.
In case you have less storage space, you will have to make efforts to Free up storage space on your iPhone.
3. Update iPhone Using Computer
If you are unable to Update iPhone using Settings, you can try to Update iPhone by connecting it to Windows PC that has iTunes installed on it.
Plug iPhone into the Computer and open iTunes (if it does not automatically start) > Click on the Phone icon as it appears in iTunes.
Next, click on the Summary tab in left-pane. In the right-pane, click on Check For Update button.
On the pop-up, tap on Download and Update.
4. Restore iPhone
If your iPhone is still not updating, the problem could be due to corruption of System Files on your iPhone.
The solution in this case is to Erase all the data on your iPhone (including corrupted files), reinstall the operating system and Restore iPhone using a previously made stable backup of your device.
You can find the steps to Restore iPhone from backup in this guide: Restore iPhone from backup.
5. DFU Mode Restore
If the regular Restore process did not help, you can try a deeper restore process known as DFU Mode Restore.
DFU Mode Restore will erase all the data on your iPhone and reinstall both iOS Operating System and also the Firmware on your device.
If DFU Mode Restore does not help, you need to get your iPhone checked by a qualified technician for Hardware problems.