I have been having a problem with my iPhone 6 Plus where it puts out an error saying the backup failed (during sync) because the iPhone disconnected. And yet it sits there still syncing. I saw a variety of solutions on the support chat boards but none of them worked or were so old I didn't try them. I am plugging directly into the Mac and not through a hub, and I have tried different ports and cables. I synced my phone with a different Mac and that worked. Deleted the backup from the primary Mac and backed up again, and that worked. I am guessing that it tries somehow to interact with the prior backup and doesn't like it, and if there is no prior backup it works. Now I can sometimes sync normally, but not always. Interested in any solutions/suggestions. Thanks.