sync failing unknown error

Can you please elaborate on where and how you located that Log File. I personally would like to give your working theory a try on my iPhone 6Plus as I am getting the same "Sync Failing Error" result with an iPhone 6Plus (128gig) w/ iOS 8.3 using Windows 7 (64 Bit) on a PC/Tower, w/ iTunes vers. 12.1.2.27

If the Problem is because I have an App on my new iPhone that is causing unknown issues with any Syncing and Backing Up my Device, then I need to resolve the issue by removing that app immediately. Which that being the case, and since you have seemed to resolve a similar issue, I would kindly like to see what process you followed to get that result. If you would be so kind as to give/share a "FULLY DETAILED" mapping of exactly what you did, where you found the log file, what routes you've taken and so on to reach that file, and what the file is called and what likely folder it would reside in, it would be Most Appreciated.

I was able to fix it.

I used Xcode to see my device's log files (cmd+shift+2, select device, bottom pane) and noticed when I enter unto storage usage details in the Settings app, some log records appears about the apps I don't have currently (in my case it was Dropbox and Litely). I tried installing those apps, but my iphone have not succeeded, leaving them in some middle state. I entered storage usage details one more time and noticed somewhere in the list there are two unnamed apps taking place, there was not any app name, but app versions exists, and they were the same like latest Dropbox and Litely app versions. So I just deleted those apps right from the storage usage and after that I was able to backup my iPhone.

Hope this helped you (and shame on Apple). 🙂

I am having the same problem but I can't install Xcode on Mavericks, what a pain, have spent hours on this and no easy solution.

Just add a thing: if you'll try just to delete this apps, without trying to install them again - that won't work.

This fixed my problem. I had called Apple Support yesterday and they didn't have a clue what might be causing it, and to be fair, it's a solution that non-developers would struggle with. I hope Apple fix this in a subsequent iOS update for those people.

This worked for me as well. Thank you!

Do you have an apple watch by any chance?

I noticed another strange log when my backup failed, mentioning an app-group that could not be found. It turned out that the apps that were causing the backup problem for me all had an apple watch version.

Thanks for the post!

This is my fix, for iPhone 6 iOS 8.4 2015

My problem was caused by a dummy app, I removed it through iPhone's SETTING, GENERAL, USAGE, MANAGE USAGE.

Look for empty app name or blank icon. Remove the app.

Try to backup again, if fail again, check for the LOG of your iTunes.

For Windows, go to

a) C:\Users\XXXXXX\AppData\Roaming\Apple Computer\Logs

b) Open the log, and see what's the problem. For my case there problem was

[11132 @ Fri Oct 09 21:27:23 2015] [com.apple.console AppleMobileBackup.exe] ERROR: Backup message response: 101 Unable to open domain directory: No such file or directory (2) at path "/var/mobile/Containers/Shared/AppGroup/8E726549-3ED1-4171-818A-12B66843C156" (MBErrorDomain/101)

c) For my case, this App " 8E726549-3ED1-4171-818A-12B66843C156 " caused the problem. So I just browse into my iPhone's directory using iExplorer, and create a folder with the same name. Note: My iPhone is jailbroken.

Then I manage to backup my phone.

Note: If you see similar error message, thats mean it's caused by an APP. Just try to delete more app and try to backup again.

Good Luck!

Your comment was the final piece of the puzzle that helped me fix my iphone backup issue. Thanks!