trying to update IOS 15.3 on 6S plus with computer. Keeps getting the message "iTunes could not back up the iPhone because the iPhone is disconnected. Please disconnect and reconnect the iPhone, then try again. In fact, the phone was connected the entire time to the computer with an original apple wire. I followed instruction to restart both the computer and phone but still get the same message after.
iPhone 6s Plus, iOS 15
Connect iPhone to Computer
Use your USB lightening cable --> Resolve USB-related alerts in iTunes - Apple Support
If unable to connect --> If iTunes doesn't recognize your iPhone, iPad, or iPod - Apple Support
For your Windows PC —> Troubleshooting issues with iTunes for Windows - Apple Community
Use genuine cable --> Identify counterfeit or uncertified Lightning connector accessories ...
See how to --> Sync your iPhone, iPad, or iPod using iTunes on your computer ...
Learn how to--> Update your iPhone, iPad, or iPod touch - Apple Support
If you are experiencing an issue not listed here, contact support
Connect iPhone to Computer
Use your USB lightening cable --> Resolve USB-related alerts in iTunes - Apple Support
If unable to connect --> If iTunes doesn't recognize your iPhone, iPad, or iPod - Apple Support
For your Windows PC —> Troubleshooting issues with iTunes for Windows - Apple Community
Use genuine cable --> Identify counterfeit or uncertified Lightning connector accessories ...
See how to --> Sync your iPhone, iPad, or iPod using iTunes on your computer ...
Learn how to--> Update your iPhone, iPad, or iPod touch - Apple Support
If you are experiencing an issue not listed here, contact support
IOS update to 6S plus
