iTunes could not backup iPhone because the iPhone disconnected

after reading a lot ways to fix this i decided to do the two easiest procedures and those seem to work for me.

1- changed the usb port

2- restarted my phone while it was connected to the laptop.

now i don't know which one did it for me but it certainly worked

I know this is a long time ago but I have just spent two days to get a solution for those who may be interested. I have a 4S and tried to back up.on itunes.

Please refer youtube by this guy https://m.youtube.com/watch?v=VyaMU09nuZQ&autoplay=1 It really makes sense.

Plus also I disconnected all from USBs except my mouse sender and switched to flight mode on the phone. At one time i turned off antivirus, but not sure if it was off when I had success. What was obvious once it was working correctly was the thin blue line at the top was slowly increasing in length and took about 3 minutes to extend fully completing the backup.

Before, it went to full length immediately- this indicates it will never backup which I did not understand at the time. Many thanks to the Youtube guy.bpchin

After disabling anti-virus to no avail, this was the only solution that worked for me.

Hi all,

"Could not backup iPad because iPad disconnected" - absolutely infuriating - I've tried every single suggestion in this thread - deleting previous backups in Mobilesync and Lockdown means it gets further in the backup process (45 mins) then crashes out. Has anybody really got to the bottom of this problem ? I have no trouble with iPhones on the same iMac ...

Cheers Max

In time, all iOS devices get this error. Some cruft isn't purged correctly, seemingly. And all tips posted are only workarounds; no really fix. I've tried everything, and the error always comes back after a couple of consecutive syncs. The only way to fix it is to clean install OSX. But even that is still a workaround, as the error will at some point simply return.

I think the engineers don't have this problem because they clean install much more frequently than their users(?)

Thanks Phil - I've given up for the time being ...

Agree somewhat. In my case, I am pretty sure it was an app (maybe corrupted) that caused it. I started removing apps and found that after a while the sync started working again. It's amazing this still isn't fixed...

If you haven't already, try putting the iPad into airplane mode, or disabling Backround App Refresh (or both!) next time if it's still giving you grief backing up the iPad.

Since you've reset all of the lockdown folder and deleted the previous backup, a likely culprit is that some files are being modified during the backup, causing it to have to back up those files over again. That shouldn't be a problem, except that the backup process tends to crash if it has to "do-over" some files more than twice. I've seen this a lot.

Thanks a lot Kelly I'll try that - also thanks to Frank but where to start with removing apps ? - I suppose I could remove a large number and reinstall next time I sync ..

It's funny reading though 22 pages of everyone's proclaimed remedies like turning off wifi and other such unrelated things.

I've been having this issue since iOS 921 and get that failed to sync message about %85 of the time I connect my phone. My wifi has not worked for over a year and recently the bluetooth part of that chip failed as well, I guess it's time to replace this 4s.

It is always a crapshoot to get the phone to actually back up but it does always sync my music, movies and other things that I don't have set to do via iCloud. In iTunes I have the backups set to my computer because they are more comprehensive than iCloud.

I have not found anything previously mentioned that works to fix this but a mix of restarting the phone and iTunes will eventually get the backup to be current. Oddly it doesn't seem to be any specific sequence that finally allows it to backup.

The phone actually does sync data even though the error message says it failed because it disconnected, at least that's the case on mine.

I agree, and don't think this error has anything to do with WiFi. Or with a specific USB port. Deleting the backup (in /iTunes/Preferences/Devices) or deleting the plist file in /private/var/db/lockdown is a silly workaround and certainly not a fix.

Using iCloud to backup is not a viable solution for me as I've never been able to restore that (successful) iCloud backup. So I'm left with an unresolved issue, which Apple doesn't seem to be willing to acknowledge and fix. Employees at the Genius Bar simply tell me I should setup the phone as new, instead of restoring an old backup, which I don't want to do because I then lose my SMS messages (from before they brought SMS syncing to OSX).

I do wonder if they'll be able to fix the missing iTunes tracks:

Apple has officially acknowledged community reports of inadvertently deleted music, with users left with missing tracks in their libraries that may never be recovered, in a statement to iMore.

Yeah people try to be helpful to a fault,swearing that this or that made it work when the reality is that it was none of the above.

I agree with you on the backup and if you look at that tab in the backup section the cloud version is only partial data, which to me is useless.

Like I mentioned earlier that error message is erroneous because the phone actually does sync, what it fails doing is backing up. This dual process is very convoluted and confusing and apple should streamline it (sync & backup). It's always a fight tomato it back up and there's no rhyme or reason but every once in a while it will actually backup and show "today" and the time. When it used to work I would do this almost every day if not every few in case my phone was lost or hosed. Not to sound like the others but all I can say is I've been able to make it happen with the roulette of either of these actions: restarting phone, quitting iTunes, unplugging the phone from usb port. It's a pita but it has been thinly way I can get a backup to update. Sit there and do it while you're doing something else so it's less frustrating!

Greg H,

"Yeah people try to be helpful to a fault,swearing that this or that made it work when the reality is that it was none of the above."

I think you've crossed a fine line here between attacking the problem and attacking people attempting to help. The work-arounds that "worked" for them, perhaps won't work for you.

This issue has been ongoing for months...without any word/acknowledgment from Apple, however, it was entirely predictable given the increased memory size and consumption of that memory by users of the devices.

Nobody has claimed that their issue has been completely resolved by any of these methods - permanently. For example, the deleting of the old backup file is a work-around designed to bootstrap the back up process by iTunes from scratch. It works - at least once - and then a few weeks later the same backup issue returns. All the original poster of this method and other's who have used it have said is that it works to at least get you ONE good backup. Which, is good enough to at least let you migrate to a new phone.

If you really want to pursue this, open a ticket under Apple Care directly with Apple and keep pushing on them.

BTW, this isn't the only extremely annoying bug Apple has with iTunes/iOS. Not having a backup of your phone is a serious matter. However, recently in an Apple Care support case I opened there's another really annoying one:

I've got a fairly expensive Bose Soundlink II BlueTooth speaker that is attached to both my MacBook Pro Retina 2013, and my iPad Mini 2. If I connect both my MacBook Pro AND my iPad Mini to the device and someone calls my iPhone...iTunes will launch (all on its own, even if it's not loaded) and begin to play a random song from my music collection. Very, very annoying since here you are trying to talk to the person who called you and this music has spun up in the background!!

I proved this to Apple Support over the phone. The only work-around, as there is a major Bug here with BlueTooth/OS X and/or Continuity...is to disconnect the Bose Soundlink II from the MacBook Pro ... not ideal, but at least I can get a phone call without being annoyed by iTunes.

I started experiencing this issue after updating to IOS 9.3.2. Couldn't resolve it, and deleting the backup, would allow me to successfully backup the first time, but upon further syncing, I would hit the same problem.

The solution that worked for me was: RESTARTING MY IPHONE! 😝

Hope this helps.