iPhone 8 fails to update from iOS 15.1 to iOS 16.7

Does it provide a reason for not updating?

Make sure you are really using an iPhone 8. To identify your iPhone model refer to the information in this article --> https://support.apple.com/108044

Includes model number variants by country.

If your device won't update, make sure you are following all the conditions for the method you are trying to use. If you are sure you are following directions correctly, try a different method.:

https://support.apple.com/HT204204 - wirelessly*

https://support.apple.com/guide/iphone/update-ios-iph3e504502/ios - with a computer

Another, less common reason for not being able to update is if you were using a beta version of software. Refer to https://support.apple.com/HT203282

If you need more space for an iOS update read this support article --> https://support.apple.com/HT203097

If your update feature on a device is greyed out or restricted, it may have been disabled using Screen Time, or by an IT administrator if you are using a device owned by an employer or educational institution. Read this article about using Screen Time on an iPhone, iPad, or iPod touch --> https://support.apple.com/HT208982

Tap Settings > Screen Time > Content & Privacy > scroll to Allow Changes.

* From ASC contributor Lawrence Finch at https://discussions.apple.com/thread/254821361?answerId=258984965022#258984965022 here's a checklist of criteria that all need to be met in order to update wirelessly:

• You need at least 10 GB of free storage for iOS 16 or 6 GB for iOS 15 or lower; more is better

• You must be connected to a Wi-Fi network (and not a personal hotspot)

• The phone must be charged to at least 50%, and preferably plugged in so it stays above 50% during the update

• The phone must not be in Low Power Mode

• The phone must not be connected through VPN, and it may be necessary to delete any VPN apps and VPN profiles

• The phone cannot be in Airplane mode and must have a cellular data connection

• You cannot still have a beta version installed on the phone

• You cannot have a previous version that was downloaded, but not installed - go to Settings/General/iPhone Storage to look; if you find an iOS installer, delete it.