I can not update my iPhone

opoku226 Said:

"I can not update my iPhone"

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OS Update Restrictions:

You can't, for your model (6 Plus). But, even if you could, updating an iPhone would only be restricted to the latest version of iOS (iOS15.6.1, as of this reply).

For future reference...

Updating an iPhone:

Determining if an Update will Install:

How to do so...

A. Verify Compatibility:

Identify your iPhone model. The first thing that comes to mind in incompatibility being the culprit. So, confirm the model of your iPhone. If iPhone model is incompatible with iOS13 and/or iOS14 and/or iOS15 then it is because you iPhone does not meet the hardware requirements for this iOS version(s).

B. If Compatible...

1. Back Up First:

IMPORTANT: If you have an option to update, however, then be certain you backup your iPhone first. That way, you will have something to restore your iPhone from should anything go wrong with the update

then...

2. Proceed with the Update:

Use my User Tip:  Update your iPhone Using a Computer - User Tip

What iOS system is installed on your iPhone at this time?

If it is iOS 12.5.6, that is as high as you can go. No additional updates are available for the iPhone 6 Plus. It's too old.