My wife’s iPhone SE (the latest iOS 12.1.1) will no longer sync with her Mac (2009 13" MBP, El Cap with the latest iTunes supported on that OS). iTunes will start the sync, but then complain that the sync “could not be synced because the sync session failed to start”. Whatever that means. Let alone give you any idea as to what you’re supposed to fix.
So after searching the web we tried a few things. Restarted iTunes. Rebooted Mac and iPhone. Deleted all the existing iTunes backups. Reset SMC and PRAM on the Mac. Rebooted Mac in Safe Mode and tried iTunes there. None of that worked. We tried syncing over USB (even tried different ports) and over wifi. In both cases the same error message.
This came pretty much out of the blue. She usually hooks it up to iTunes about once a week to do a backup and sync. The last iTunes backup carried that time stamp so until most recently everything worked just fine. I cannot recall any software updating activity within the last few months on her old Mac. And the iPhone hasn’t done anything apart from the 12.1.1 update. I did that too and I’m not encountering any of these issues on my Mac.
So now she cannot sync iTunes content to her iPhone. She can no longer back up her iPhone. It’s a mess. And of course iTunes offers zero indication as to what the user should do to fix the issue. That was her backup. If her phone falls under a truck all her data will be gone. Right now she’s really SOL. Any ideas?