The following error message appears while backing up your device in iMazing or iTunes.
"Cannot backup your device. Couldn't start sync session"
This error message appears when the device's pairing records stored on your computer are corrupted.
- Quit iTunes if it is running.
- Launch iMazing and Forget your device. To do so, right click on your device in iMazing's left sidebar and click "Forget" in the contextual menu.
- Disconnect your device.
- Reboot both your computer and your iOS device.
- Try backing up now - note you'll have to pair the device again, with iMazing or iTunes.
For instructions on how to forget your device in iMazing, see our article: Connect your device to iMazing