I have a mid 2011 iMac. I'm not allowed to upgrade to Catalina. My iMac and iMac are all running the latest software (i.e. they are up to date). The iMac is on Sierra.
I can't backup my iPhone 8 Plus to the iMac anymore. The functionality has been removed from iTunes (which I still have). I don't have 'Music'. Help, because I cannot find any advice anywhere
iPhone 8 Plus, iOS 13
The iTunes backup will still work with the latest iOS, but as I recall iTunes had to upload some kind of helper. Sadly I can't remember exactly what I did to trigger the helper, but I was sighed out of iCloud on my iOS devices and I had to re-select Back up all ....... to this Mac instead of iCloud.
also see > How to back up your iPhone, iPad, and iPod touch - Apple Support
If you use iCloud your phone is always backed up!
Backing up iPhone to iMac
