iTunes could not backup iPhone because the iPhone disconnected

It’s quite frustrating to me, the time that I have spent researching how to fix apple’s mistakes, as well as the fact that I still can’t quite simply sync all of my music to my highly expensive phone. Also what angers me is that I have to spend my time ranting about these issues on a post that I’m not even sure will do any good. I’ve had many issues getting my phone to back up because it “disconnected”, when clearly, the phone is still connected to my computer. Also, after trying the plethora of presumably possible fixes to get music to actually play from my phone, and it not working, I just feel like throwing my hands in the air and crying. Apple, please make your products work properly. Why should I have to list all the problems I’ve had, as well as when I’ve had them, as well as what has worked and NOW doesn’t. Apple, don’t put out a product that doesn’t work right.

This is so frustrating to me. As an consumer of the apple culture, I've tried multiple means to back up my iPhone to not only my computer but the cloud. I've deleted prior back ups, changed the folders, synched in airplane mode, etc. To no avail. The nuclear option is to put my phone back into factory mode, but if I can't backup my photos/settings, its going to waste a lot of time. Apple really is not responding to this thread. Its a problem. I am not sure why they cannot fix it.

The "iPhone cannot back up because iTunes disconnected" is painful message. Everything is connected. I've tried multiple computers. I wait for nearly 20 minutes for the back up to complete, then this error message. What is the work around???

TThanks Lawrence for the exact location and the suggestion on fixing the deletion of backup.

I copy out the previous backup to another folder. Delete the backup, then backup again. It works!

thanks again to all the teacher here!

Also Just to add if your running on PC try using the USB socket on the back on the case as the front sockets produce less power to your device.

When I hold down the sleep button nothing happens, also when I connect the phone a dialog box appears "iTunes could not connect to the iPhone because it is locked with a passcode. You must enter your passcode on the iPhone before it can be used with iTunes." but i really cant. i can't even force restart it or put it in recovery mode. pleasae help me. stuck on iphone is disabled, connect to itunes.

YES!! This worked perfectly for me -- turning off the wifi on my phone solved the issue and i was able to back for the first time in 2 months! Thanks!

NOTE for windows users. I deleted all back ups but it still did not solve my problem.

I have an HP Envy 15 notebook, which has four USB 3.0 ports, one USB 2.0 port. After latest 9.2 upgrade and iTune 12.3.2.35 only USB 2 port is working successfully for sync. All USB 3.0 ports fail with this error

If you see this error as well while sync your iPhone/iPad try a USB 2.0 port if you have the option

I had a similar problem with my iPhone 6 (iOS 9.2.1) and iTunes (12.3.2)

I tried deleting the previous back-ups, but the problem kept coming back. It got to a point where i could not even backup even after I had deleted the back-ups via iTunes/Preferences/Devices. I had to go into ~/Library/Application Support/MobileSync/Backup to figure out which was the backup for my iPhone and delete that particular folder. Even then, the problem came back after I had backed up the phone once.

I came across another thread and it got me thinking that it could be a corrupted app that is causing the problem. I went through all the apps on my phone to try to figure out which was the one i had installed recently that may have caused the problem. And then i found it. It was an app that i had installed outside of the AppStore. I figure since Apple curates the apps stringently, it is unlikely (but not impossible) that they would allow one in that might corrupt the ecosystem. So i deleted the offending app, and tried again, and lo and behold, everything worked as it should be!

In iTunes preferences - Devices, I had a backup that showed a padlock icon next to it, this was the last backup I made before I had this problem, so I deleted this one (which was quick) and then manually made another backup (which took a while as it was a full backup and I have a lot of pics & music) but this resolved the issue. Thanks a million !!!

I reset all settings on my iPhone and deleted 2 old backups (not the most recent one) and it worked fine afterward.

While deleting either the current backup or the .plist in /private/var/db/lockdown does indeed fix it, this is only a temporary as the issue will return after a few syncs.

Yes I found this happened to me as well, but it doesn't happen every time. Now if I get the same error I try to sync again and it usually works, if not I restart iTunes and/or the PC and so far this has been working for me.

If anyone finds a permanent fix, please let me know.

connecting to the back of the tower seems to have worked. I noticed whenever the fan on the tower would turn on it would disconnect my phone when using the front port

My Case.. just

1. turn off wifi on the phone.. and

2. do the backup again can solve the problem.

hope it helps ~!