The iPhone could not be synced because the sync session failed to finish.

I'm sorry to hear that you're having trouble syncing your iPhone. There are a few potential solutions that you can try if you're encountering this error message. Here are a few things you can try:

1. Restart your iPhone and your computer: Sometimes, simply restarting your devices can help resolve sync issues.
2. Check your USB cable and port: Make sure the USB cable you're using to connect your iPhone to your computer is in good working condition and try a different USB port on your computer.
3. Check for updates: Make sure that you have the latest version of iTunes and that your iPhone is running the latest version of iOS.
4. Check your security software: If you have security software installed on your computer, it might be blocking the connection between your iPhone and your computer. Check your security software settings and make sure that it is not blocking the connection.
5. Reset your iPhone: If none of the above steps help, you might need to reset your iPhone. This will erase all data from your iPhone and restore it to its factory default settings. You can then try syncing your iPhone again.
6. Use another sync method: If you're still having trouble syncing your iPhone, you might want to try using a different method, such as iCloud or a third-party tool like iMazing or AnyTrans.

I hope these suggestions help! If you're still having trouble syncing your iPhone, it might be helpful to get in touch with Apple support for further assistance.