Error while installing ios 15.5

Check iPhone type & iOS version -> Go to: Settings -> General -> About.

If it is an iPhone 6 Plus -> iOS 12.5.5 is the last security updates for iPhone 6 Plus, -> released 23 september 2021.

If it is an iPhone 6S Plus you can update the iPhone to iOS 15, see this Apple article:

iPhone models compatible with iOS 15

iPhone models compatible with iOS 15.4 – Apple Support (UK)

Go to: Settings -> General -> Software Update.

See the following Apple articles:

Update your iPhone, iPad, or iPod touch

Update your iPhone, iPad, or iPod touch - Apple Support (IN)

If your iPhone, iPad or iPod touch won’t update

If your iPhone, iPad, or iPod touch won't update - Apple Support

You can do the update via PC, see this Apple article: Update software on iPhone, iPad or iPod touch in iTunes on PC

Update software on iPhone, iPad or iPod touch in iTunes on PC – Apple Support (UK)

If you have a Mac see this Apple article: Update your iPhone, iPad, or iPod touch with the Finder

Update your iPhone, iPad, or iPod touch with the Finder - Apple Support

You need about 7 GB device storage and good Service & Wi-Fi.

If they are On, turn Off Hotspot & VPN.

sos77 Said:

"Error while installing ios 15.5: Downloaded ios 15.5 and trying to install I got an error"

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For reference...

Updating an iPhone:

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 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:

Go Here:  Update your iPhone Using a Computer - User Tip