I'm using iTunes 12.9.5.5 on Mojave (fully updated, to my knowledge). For six months my iPhone 8 (then on iOS 16.5) has not been able to backup to it, neither using USB nor WiFi.
- Sync seems to work fine otherwise.
- Older versions of iOS 16 seem to have backed up successfully, judging by last backup date.
- The error received is my language's equivalent of "…an error occurred while reading from or writing to the iphone".
- The backup should be smaller than the free space left on the destination volume (~100% margin), judging from the backup size when performed successfully on Windows.
My latest troubleshooting steps have been:
- Updating to iOS 16.6
- Trying an older (lower version: 12.6.3.6, older copyright year: 2017) iTunes version on Windows, which successfully performs the backup
- Try backing up an old iPhone 5 with iOS 10, which works
After these tests I'm left wondering whether this version of iTunes is supposedly capable of performing said backup at all? Can I confirm this somehow? That a lower version on Windows can perform a backup confuses matters somewhat, but the versions might not be directly comparable so I'm left guessing.
Note that this question is specific to macOS Mojave, and as such upgrading to later major releases of macOS is out of scope as a solution.
Best Answer
Empirically, yes, using these settings, connected by USB.
Mac Pro 5,1, Mojave, iTunes 12.9.5.5, iPhone SE2020 iOS 16.6. The phone demands trust with a light grey passcode screen before it will start & then sits with a full progress bar [thermometer] for a minute or two before then progressing normally.
I normally only do a local backup manually just before an update, so I hadn't tried since end of July. I don't have auto-sync or sync over wifi on.