Can I update my iPhone 6s to iOS 15?

There are only 2 ways to update an iOS/iPadOS. Know how to...

• Update Over-the-Air (OTA) —> Update your iPhone or iPad - Apple Support (IN)
• Update using iTunes/Finder —> Update your iPhone, iPad, or iPod touch - Apple Support (IN)

Before any iOS / iPadOS update, please do the following

• You need to Identify your iPhone model - Apple Support
• It is also recommended that you either take a backup on iTunes or iCloud --> How to back up your iPhone, iPad, and iPod touch
• If you have a beta profile installed, remove the public beta by deleting the beta profile

Go to Settings > General, and tap Profiles & Device Management. Tap the iOS Beta Software Profile. Tap Remove Profile, then restart your device --> How to uninstall iOS beta software - Apple Support

VPN or proxy connections might prevent your device from contacting the update servers.

• Get help with over-the-air iOS updates - Apple Support
• Remove and download the iOS update again

If you still can't install the latest version of iOS, try downloading the update again:

1. Go to Settings > General > [Device name] Storage.
2. Find the iOS update in the list of apps.
3. Tap the iOS update, then tap Delete Update.
4. Go to Settings > General > Software Update and download the latest iOS update.

If you don’t see the update in the list of apps or if the issue happens again, you need to update your device with iTunes.

Try updating iOS after each step.

• Try to Forget the WiFi network and add it again
• Try another WiFi network 
• Toggle sets automatically off and then on
• Reset your network settings
• Force restart your device
• Remove any beta profiles, if applicable

• If everything fails: - Use iTunes or Finder (for macOS Catalina+) to update your device instead of over-the-air
• Get help with iOS updates and restore errors - Apple Support
• If you see an error when you update or restore your iPhone, iPad

You need to correctly Identify your iPhone model - Apple Support

These are the iOS options based on iPhone Model -->

• iOS 16.1.2 —>
  • Chipset A11 - 8 / 8 Plus / X
  • Chipset A12 - XR / XS / XS Max
  • Chipset A13 - SE (2020) / 11 / 11 Pro /11 Pro Max
  • Chipset A14 - 12 Mini / 12 / 12 Pro / 12 Pro Max
  • Chipset A15 - SE (2022) / 13 Mini / 13 / 13 Pro / 13 Pro Max
  • Chipset A16 - 14 / 14 Plus / 14 Pro / 14 Pro Max
• iOS 15.7.1 —>
  • Chipset A9 - 6S / 6S Plus /SE (1st Gen)
  • Chipset A10 - 7 / 7 Plus
• iOS 12.5.6 —>
  • Chipset A7 - iPhone 5S
  • Chipset A8 - iPhone 6/6 Plus
• iOS 10.3.4 —>
  • Chipset A6 - iPhone 5
• iOS 10.3.3 —>
  • Chipset A6 - iPhone 5C
• iOS 9.3.6 —> iPhone 4S - Chipset A5
• iOS 7.1.2 —> iPhone 4 - Chipset A4

Know how to...

• Update Over-the-Air (OTA) —> Update your iPhone or iPad - Apple Support (IN)
• Update using iTunes/Finder —> Update your iPhone, iPad, or iPod touch - Apple Support (IN)

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)

iPhone 6s, iOS 11

If it is an iPhone 6 you can update to iOS 12.5.6. 

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

Go to Settings -> General -> Software Update -> Download and Install.

If it is an iPhone 6S you can update to iOS 15.7.1.

You need about 5 GB device storage and good Service & Wi-Fi.

If they are On, turn Off Hotspot & VPN.

Charge the battery > 70%.

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