iTunes could not backup iPhone because the iPhone disconnected

Reset network works for me.

Updating my original list with a few more things to try if you're having consistent problems making a backup.

One problem that is probably well addressed in this thread is a broken previous backup. In those cases deleting (or archiving, so you don't lose it) the previous backup will push the issue through. This is the most frequent cause I see for the problem.https://support.apple.com/en-us/HT203282 (Just the section entitled "Archive an iOS backup with iTunes")

Another common problem is a flood of notifications during the backup causes the backup process to need to restart enough times that it eventually just crashes the backup program. You'll frequently see this one produce a message about the iPhone disconnecting. You can try putting the device into Airplane Mode in order to test/prevent this cause.

In Kiwimacguy's case, there's an intermittent problem using the iPhone's keychain, that causes the backup to fail sometimes and succeed other times. At some point, changing the lock screen password just wreaked havoc that only a backup restore could fix, but the root cause definitely seems hardware related. This is likely a more rare cause of this error message.

On Windows computers, there seems to be an increase in USB connection problems beyond just a faulty cable (although cable problems are frequent too). I haven't quite put my finger on the root of this issue enough to post here yet, but I've been seeing it happen a lot more over the past few weeks. If you haven't tried already, try switching out the cable, switching USB ports, rebooting the iPhone, and resetting the Windows sockets ("netsh winsock reset" in an admistrator command prompt.)

Another way to resolve some USB or wifi connection problems that may mess up the backup is to Reset Network Settings from Settings -> General -> Reset.

Several people have reported incorrectly installed apps causing their backups to consistently fail. In this case, open the Settings app -> General -> Usage -> Manage Storage and look through your installed app usage. (It may take a moment for the list of apps to appear.) Look for apps named "Null" or with no name. These apps need to be removed for the backup to proceed. Here are two other forum posts about this specific issue. "Null" app can't be deleted and Backup fails at step 4

I had all sorts of problems getting a local backup to my imac over USB to work. Thought I'd post what worked for me here.

- Official Apple thunderbolt table (this is a 6 plus)

- Plug directly into the imac not into a hub

- Turn off wifi on the phone

- Delete the previous backup

- Reboot the phone - Kept getting disconnected even with the above steps until I rebooted then did a full sync and the backup worked this time.

Hope this helps...

I've been suffering silently with this for some time. Along the way, I learned to nuke the existing backup to get a new backup.

But that's not exactly a solution. So, today, as I wait for my new 6s plus, I'm experimenting a bit and may have found at least some interesting signal to add to the discussion. Here's what I did.

1. Created a new admin user account - test iTunes - on my MacBook.

2. Declined the offer to login with my iCloud account.

3. Synced my phone to the new account.

4. Sync worked.

5. (this may be an unrepeatable anomaly) I disconnected iPhone, used it for a bit, then reconnected for the second, incremental backup. It failed. At the same time, I had the backup folder open in the finder and noticed that Finder had hung. I force-restarted Finder.

6. I attempted to run the incremental backup after restarting Finder. IT. WORKED. My last backup is now time-stamped 11 minutes after the first.

I didn't do any of the other voodoo mentioned up-thread. Did not reset network settings. Did not invoke Airplane Mode. Did not sacrifice a chicken.

No idea if this holds going forward. Also, this afternoon I'll have some new hardware to test it on. So there's that.

And, just like that, it's failing again. Creating a fresh user account appears to be unrelated.

same issues here. I've tried everything in this thread spanning the last 3 years. this problem is really a bummer. Been trying to get around this issue for 3 days- and now I have an iPhone 6s sitting on my desk unopened because I can't get my **** iPhone 6 backed up properly.

nismo95tt, try doing all the suggestions at the same time.

1. Copy the backup from the backups folder saving it somewhere else and then delete the backup in:

users/yourusername/library/Application Support/MobileSync/Backups/

2. Reboot computer

3. On your iPhone Settings/General/Reset/Reset Network Settings

4. Use your new iPhone USB cable that came with your new iPhone 6s to try backing up your phone in iTunes

You should be able to get one backup in before it breaks again if it's indeed the same problem many of us are having.

So far, through one full and three incremental backups, this appears to be working with the new 6s plus. It must have been some ghost in the machine that was somehow tied to the presence of my old iPhone 6.

One other detail I'm remembering: This started when I loaded a developer beta of one of the incremental iOS 8 versions. There was a general release note that encrypted backups were failing in that version. Come to think of it, that's when the "iPhone disconnected" issues started for me and never went away until I switched hardware.

My admittedly uninformed suspicion: Even though the encrypted backup issue was fixed for nearly everyone eventually, my particular phone was forever corrupted at some very low level because of this. Maybe a complete erase and restore could have solved, but it was never such a big issue that I went that far. Buying a new phone was an effective albeit extreme replication of that fix.

Is anyone with this problem NOT doing an encrypted backup?

I've had the same problem for a while (iPhone 5s, running IOS 9 but had the problem with 8; iMac with OSX 10.10.5). I could force a new backup by archiving the old backup, but incremental backups were failing with the "disconnected" error. I just tried the Reset Network Settings and that appears to have fixed it. Thanks for the helpful post.

I found that a simple solution is to enable Airplane mode and try again. It seems that if wifi sync is on and you are connected via usb as well, the Iphone gets confused,

I know this may be very late but, for anyone who comes across this post because they are having current issues... I was able to fix mine by disabling the automatic lock on the phone, disabling the automatic sleep mode as well as the screen saver on my computer, and I plugged the iPhone into the back of the computer instead of to the front of the computer. Hope this helps. I spent way too long trying to figure this out and suddenly it just hit me!! (Homer- DOH!!)

Good to read. My solution was different:

https://support.apple.com/en-us/HT203887

Nothing have helped me yet. I've tried on other computers "without transferring purchases" option and it takes my backup perfectly. But, opting for transferring purchases i think is the main issue. I've visited some apple service centres , they also have less knowledge about it.

I did all "erasing network settings" , "erasing settings" etc. nothing helped.

Jindal.ashish27 wrote:

Nothing have helped me yet. I've tried on other computers "without transferring purchases" option and it takes my backup perfectly. But, opting for transferring purchases i think is the main issue. I've visited some apple service centres , they also have less knowledge about it.

I did all "erasing network settings" , "erasing settings" etc. nothing helped.

If you choose Transfer Purchases from the Devices menu, does the Transfer Purchases alone (with no backup) work, or give you an error?

Thanks a lot Lawrence... now I definitely enjoy more the iTunes experience...!🙂