iTune could not restore the phone because backup was corrupt

If for some reason updating your current device to the latest iOS doesn't end up solving your problem, Apple has additional tips here https://support.apple.com/en-us/HT203271 and there is also blog that has instructions specifically related to the "iTunes could not back up the iPhone because the backup was corrupt" error message at https://deciphertools.com/blog/fix-iphone-backup-corrupt/

Sometimes you wrongly get that error message only because the new iphone is running an iOS version earlier than the one that was used by your old device to create the backup.

Check that. Should be this case, before restoring, you need to update your new iPhone to the latest release (now 12.2).

Regards

Giulio