Why can’t I update my phone to iOS 15?

An iPhone 7 plus is capable of running iOS 15.7.3

What happens when you try?

Can you post a screenshot of the whole screen, it could reveal why you aren't able to update.

Make sure you:

• Are using a WiFi connection (not a hotspot).

• You have an active cell signal (You need both WiFi and cellular service to perform the upgrade).

• Are not using a VPN connection.

• Have your battery charged at least 50%. Better yet, keep it plugged in during the update.

• Do not have power save mode turned on.

• Do not have a beta version installed.

• You have at least 10 gigs of storage available.

Click on this link on what to do if you can't update your phone -

If your iPhone or iPad won't update – Apple Support (UK) If your iPhone or iPad won't update – Apple Support (UK)

If yours is an older phone it may not be eligible for the upgrade you are trying to get. You haven't mentioned what model phone you are trying to upgrade to what iOS version, so that is about all I can suggest.

If you're running low on space, you can update using a computer which requires less space than updating wirelessly.