I can’t update my iOS... its not working

iPhone 6s can get as far as iOS 15, and no further.

Here is how to: Update iOS on iPhone - Apple Support

Remove any beta profile, remove any add-on VPN client app, free up enough storage for the upgrade, force restart, connect to Wi-Fi and not hotspot, and try again.

If that fails, use a computer to upgrade your iPhone. (That’s linked in the above update article.)

Also see: If your iPhone or iPad won't update - Apple Support

Your stats say you're running iOS 12.

If this is true, then you don't have an iPhone 6S, you have a 6 or 6plus which can't be upgraded beyond 12.5.7.

Good morning.

Almost every year Apple "cuts" important updates to an iPhone model for compatibility issues. However, Apple still keeps making security updates even after the "cut" for a few years. Here is the list of the last 4 important iPhone-compatible updates (updated March 2023):

iOS 16:

1) iPhone 14 Pro Max

2) iPhone 14 Pro

3) iPhone 14 Plus

4) iPhone 14

5) iPhone 13 Pro Max

6) iPhone 13 Pro

7) iPhone 13 Mini

8) iPhone 13

9) iPhone 12 Pro Max

10) iPhone 12 Pro

11) iPhone 12 Mini

12) iPhone 12

13) iPhone 11 Pro Max

14) iPhone 11 Pro

15) iPhone 11

16) iPhone XS Max

17) iPhone XS

18) iPhone XR

19) iPhone X

20) iPhone 8 Plus

21) iPhone 8

22) iPhone SE (3rd generation)

23) iPhone SE (2nd generation)

iOS 15, iOS 14 and iOS 13:

iPhone 13 Pro Max (iOS 15)

iPhone 13 Pro (iOS 15)

iPhone 13 Mini (iOS 15)

iPhone 13 (iOS 15)

iPhone 12 Pro Max (from iOS 14)

iPhone 12 Pro (from iOS 14)

iPhone 12 Mini (from iOS 14)

iPhone 12 (from iOS 14)

iPhone 11 Pro Max (from iOS 13)

iPhone 11 Pro (from iOS 13)

iPhone 11 (from iOS 13)

iPhone XS Max

iPhone XS

iPhone XR

iPhone X

iPhone 8 Plus

iPhone 8

iPhone 7 Plus

iPhone 7

iPhone 6s Plus

iPhone 6s

iPhone SE (3rd generation)

iPhone SE (2nd generation)

iPhone SE (1st generation)

If your iPhone is compatible with the version you want to install, you can try to perform a forced reboot, even if I don’t think so. To do this you must follow this procedure:

iPhone 8 and following:

Press and release the Volume Up button quickly

Quickly press and release the Volume Down button

Long press the Side Button (power) until the Apple logo appears

iPhone 7 and 7 Plus:

Press the Volume Down button and the Side (Power) button simultaneously with a long press until the Apple logo appears

iPhone 6s and following:

Long press the Side (power) button and the Home button simultaneously until the Apple logo appears

At this point try to update.

If there are still problems, try connecting your iPhone with a cable to a Mac or PC with iTunes.

Now:

1) If your Mac has MacOS 10.15 or later: Open the Finder and select your iPhone in the sidebar, click "Check for Updates", select an available update, and click "Update".

2) If your Mac has MacOS 10.14 or earlier or is a Windows PC: Open the iTunes app, click the iPhone-like button at the top left of the iTunes window, then click "Summary". Then click "Check for Updates", select an available update and click "Update".

I hope I helped you!

Yes, I understand that, however, due to the issue he is having updating his system, I thought I would point out the possibility of him having a 6 or 6plus phone that can't be updated beyond 12.X

Kurtosis12 wrote:

Your stats say you're running iOS 12.

If this is true, then you don't have an iPhone 6S, you have a 6 or 6plus which can't be upgraded beyond 12.5.7.

iPhone 6s first shipped with iOS 9.0, and tops out at iOS 15. Yes, this can be an iPhone 6s from the footer, and still running iOS 12. This would be iPhone 6s that hasn’t been updated in a while, and that for any of various reasons. As a guess, this is probably also the iPhone 6s with the 16 GB configuration, too.

What message appears when you try to run the update?

If you could provide a screenshot.....if possible.....that would be really helpful.

A screenshot would answer a lot of questions, and it was requested. Hopefully, the OP will provide that.