iPhone 16 "The operation could not be completed An unknown error occurred (1852797092)

You may try some of these steps, please check after each step...

1. Reset Network Settings: Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings: Only network settings are removed.
   1. When you reset network settings, previously used networks and VPN settings that weren’t installed by a configuration profile or mobile device management (MDM) are removed. Wi-Fi is turned off and then back on, disconnecting you from any network you’re on. The Wi-Fi and Ask to Join Networks settings remain turned on.
   2. To remove VPN settings installed by a configuration profile, go to Settings > General > Profiles & Device Management, select the configuration profile, then tap Remove Profile. This also removes other settings and accounts provided by the profile. See Install or remove configuration profiles on iPhone in this guide.
   3. To remove network settings installed by MDM, go to Settings > General > Profiles & Device Management, select the management, then tap Remove Management. This also removes other settings and certificates provided by MDM. See “Mobile device management (MDM)” in the iOS Deployment Reference.
   4. Reset your Network Settings. Tap Settings > General > Reset > Reset Network Settings. This also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that you've used before.
   5. 
2. If the issue persists, you can try resetting all settings on your iPhone. This will not erase your data but will reset all personalized settings to their default values. Go to Settings > General > Transfer & Reset > Reset > Reset All Settings and confirm the action. Note that you will need to reconfigure your settings afterward. All settings—including network settings, the keyboard dictionary, the Home screen layout, location settings, privacy settings, and Apple Pay cards—are removed or reset to their defaults. No data or media are deleted.
   1. Reset All Settings: Return iPhone settings to their defaults - Apple Support:- Return iPhone settings to their defaults
   2. You can return settings to their defaults without erasing your content.
   3. If you want to save your settings, back up your iPhone before returning them to their defaults. For example, if you’re trying to solve a problem but returning settings to their defaults doesn’t help, you might want to restore your previous settings from a backup.
   4. 

Ensure you're logged into your Apple ID under Settings > [Your Name]. If there’s any issue with the account, try signing out and signing back in.

See this --> If you see an error when you update or restore your iPhone, iPad or iPod - Apple Support (IN)

Or this --> iOS update and restore errors - Apple Support

Error 53 --> If you see error 53 when you update or restore your iPhone or ...

Error 9, 4005, 4013, 4014 --> If you see error 9, 4005, 4013, or 4014 when you restore your ...

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

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

Here are some things you can try:

Basic checks:

• Make sure your iPhone is connected to a stable Wi-Fi network. A weak or intermittent connection can cause update issues.
• Ensure your iPhone has enough storage space. The update might not be able to download if your storage is full. Go to Settings > General > [Device name] Storage and see how much space you have available. If you need to free up space, delete unnecessary apps or files.
• Force restart your iPhone. This can clear any temporary glitches that might be causing the problem. For an iPhone 7, press and hold the Sleep/Wake button and the Volume Down button simultaneously until you see the Apple logo.
• Sometimes, a simple restart can resolve temporary software glitches. Turn off your iPhone, wait for a few seconds, and then turn it back on.

1. 1. Restart the device. That's it.
   2. Still not solved --> Force restart iPhone - Apple Support

More advanced troubleshooting:

• Update your iPhone using a computer. Connect your iPhone to your computer with a reliable cable and open iTunes (or Finder on macOS Catalina or later). Select your iPhone in iTunes/Finder, click "Check for Update", and then download and install the update. Update your iPhone, iPad, or iPod touch - Apple Support (IN)
• Restore your iPhone. This should be a last resort as it will erase all of your data and settings. Make sure you have a recent backup before you proceed. Return iPhone settings to their defaults - Apple Support (IN)