iTunes Can't Backup Due to Unknown Error

Discussion in 'iPhone Tips, Help and Troubleshooting' started by fraggot, Jun 23, 2010.

  1. macrumors 6502

    Jun 16, 2009
    Cox's Creek, KY
    I had to recently sync my iPhone 3G with my Mac cause my PC was having some issues. It was working just fine, syncing fine and everything.

    Well I finally got my PC working again and completely restored as a new phone on my PC and now it refuses to back up.

    It gives me "iTunes cannot back up the iPhone because an unknown error occured (-20)" and can't seem to find anything on the internet with this error. Is anyone else experiencing this at all or is it just me?

    I'd really like to be able to backup my phone just in case something happens. I'd continue to sync with my Mac Mini but it's an older model(with only 80gb of storage) and all my 200gb of music is stored on my PC so that's not my best option.

    Any ideas?
  2. macrumors 68020

    Oct 12, 2006
  3. thread starter macrumors 6502

    Jun 16, 2009
    Cox's Creek, KY
    I do, I originally had it synced with my PC. After updating to 4.0 was when my PC had issues and switched to my Mac. Now going back to my PC is where I'm having the problems.
  4. thread starter macrumors 6502

    Jun 16, 2009
    Cox's Creek, KY
    Hmm so I guess no one else is experiencing this problem?
  5. macrumors newbie

    Jun 12, 2010
    I got that exact same error.

    It seems that it started only after updating to iOS 4 which leads me to think its an iOS specific problem, but other than that it syncs just fine.

    been looking for a fix since Monday, although having the GM seed installed last week didn't leave me with any problems at all.
  6. macrumors newbie

    Jun 25, 2010
    Same issue after syncing my old 3G (3.1.3)

    I have two iPhones, my old 3 G and my new iphone 4. I am giving my older phone to one of my kids and wanted to give them a fresh install of 3.1.3. I can no longer back up my iPhone 4. Same error.
  7. macrumors member

    Jul 10, 2008
    i had an issue with syncing. The phone kept freezing up my iTunes everytime it synced. I had to get the phone replaced because its a software issue within the phone. Not sure if this helps...
  8. macrumors 6502a


    Dec 4, 2009
    West Koast
    I'm using iTunes 9.2 on my Snow Leopard MacBook, and my iPhone4 won't sync either, it gives me an "Unknown Error (-39)." message. :confused:
  9. macrumors 6502a


    Dec 4, 2009
    West Koast
    Thanks to a September 09 posting by MacRumors member Remora, here is his solution for the "Unknown Error (-39)" error and it works!!

    Thanks to MR member Aggie for pointing it out to me.

    An easier and quicker way.

    This error is associated with your iPhoto library.

    Navigate to <username>/Pictures/iPhoto Library

    Right-click on iPhoto Library and show package contents.

    Remove the folder iPod Photo cache (delete it, move it to Trash or whatever you want - just remove it from the iPhoto Library!)

    Sync your iPhone. The photos will reverify and, bin go, you're done.

    I had 3833 images and it took less than 10 minutes.

    All fixed.
  10. macrumors newbie

    Jun 25, 2010
    Finally, success :D

    After a lot of forum reading, trial and error, my new iPhone 4 is finally backing up and syncing without errors.
    I simply went into itunes and under Devices and removed the last iPhone 4 back up. That's it, no more unsuccessful syncing or bad backups, everything is back to normal and I have a new back up of my device.
    Hope this helps someone else out there.
  11. macrumors regular

    Jun 18, 2010
    I get the error:

    "iTunes could not back up the phone "XXX's iPhone" because a session could not be started with the iPhone"

    Anyone seen and fixed that one? I tried removing the old backup file and no dice. This is a 3gs running iOS 4.
  12. macrumors newbie

    Jun 28, 2010
    Me Too!!!

    I am having a problem in that my iPhone and my iPod touch are not backing up during their syncs, it's just not even trying to back up, they will sync fine, then when you try to goto the backup's, there is nothing there!

  13. macrumors newbie

    Jun 30, 2010
    Same (-20) Error: Now Resolved!

    I too had the same (-20) error after upgrading my 3GS to iOS 4.0.

    I was performing a sync when my computer froze. I rebooted, tried to sync again and iTunes went through the motions: backing up, syncing etc. however at the end I received the "iTunes cannot back up the iPhone because an unknown error occured (-20)" error.

    I removed all the app crash logs, deleted the last few backups, all with no joy.

    A week later I was still receiving the error, so I bit the bullet and deleted all of my backups, and now it works with no issues!

    Hope this helps someone.
  14. macrumors newbie

    Jul 21, 2010
    iphone 4 backups

    Hi Guys (first post from me),
    Im still getting the 'itunes could not back up the iphone because an unknown error occurred (-20).' error. Ive checked my backup history and dont have any stored - so it looks like Ive never been able to back up. Sync works fine however.

    running XP / ITUNES / Iphone 4

    any help would be lovely please.
  15. macrumors newbie

    Jul 5, 2010
    I have been having trouble since I updated iTunes yesterday. I was unable to complete sync since then and have tried restoring phone. I think it's tanked now -- I went to bed with it trying to restore last night and it's been over 14 hours now so don't think it's going to do anything.

    Original messages were "The iPhone "x" cannot be synced. An error occurred while writing to the device." and "The iPhone "x" cannot be synced. The required disk cannot be found." Going to delete the photo cache as mentioned above and try one more time before going to Apple store.

    Edit: Errors finally fixed by deleting the ipod photo cache as described in this thread. Thanks!
  16. macrumors newbie

    Jul 24, 2010
    I'm an iphone 4 virgin. Phone will not update or back up - keep on getting unknown error -20. have tried deleting photo cache and this did not work. How do I access back up history on devices.
  17. macrumors newbie

    Jul 24, 2010
    I've found the solution


    Not sure if this is old news but this is how I solved the error(-20) in iTunes (i.e Unknown error - not backing up) (I have an Ipod Touch - (OS 4).

    All I did was navigate in Explorer/My Computer on XP to:—
    C:\Documents and Settings\(username)\Application Data\Apple Computer\MobileSync\Backup

    A quick Google will tell you where the Backup is stored on other OSs

    Cut (remove) the folder 'Backup' and save it somewhere safe (just in case).

    Disconnect your iPod

    Stop the following services (Control Panel, Administrative Tools)

    ITunesHelper.exe and iPodService.exe (anything with iPod or iTunes
    basically)(not really sure if this is necessary but it's what I did)

    Reconnected my iPod (USB device not worries)

    iTunes started and created a new Backup folder and hey-presto it's all rosey!

    I hope this helps.
  18. macrumors newbie

    Jul 29, 2010
    try different USB port

    My mate had a problem with this today and a different USB worked
  19. macrumors newbie

    Aug 13, 2010
    Solution to unknown error (-20)

    My first post but I am writing to confirm previous posts with the solution to the problem. After updating my 3GS to iOS 4 I began having problems backing up my iPhone, getting the "iTunes could not back up the iPhone because an unknown error occurred (-20)" message. It seems the previous backup files from my previous iPhone OS were causing problems. As someone else on here posted, going through windows explorer and manually finding and removing the old backup files from their current directory (I just moved them to another location on my hard disk) did the trick. Right after I retried to backup my iPhone and am now having no further problems. For those who are having the same problem the filepath is C:\Users\user\AppData\Roaming\Apple Computer\MobileSync\Backup. Be aware the folder "AppData" is hidden and you will need to be sure you go into the control panel and make sure hidden files are shown. Just remove the old backup files and you should be OK. Thanks for the tips everyone and I hope this post helps someone.
  20. macrumors newbie

    Sep 2, 2010
    Confirm MadMax1991's fix on PC for Error (-20)

    Using Win 7. Got the "unknown error (-20)" message. Simply went to the directory as noted in MadMax1991's fix and renamed the BACKUP directory to BACKUP_ABANDONED. Restarted iTunes and it created a new BACKUP directory and completed the process successfully. There had been no notable changes to the iPhone's configuration. However, since my last sync I had loaded considerable new software on the PC, including Windows Virtual PC. I have no indication as to what caused the glitch. Thanks to all for the assistance.
  21. macrumors newbie

    Jun 21, 2009
    Unknown error

    I've had the unknown error challenge a couple of times since I've had an iPad 1.

    The technique related to going into the iphoto library posted by Eldiablojoe
    macrumors 6502a has worked both times for me.

    Stan, an American in France
  22. macrumors newbie

    May 29, 2011
    with my itunes, i can't have a account without credit card ? what can i do ?
  23. macrumors newbie

    Jan 4, 2010
    Deleting Ipod Photo Cache worked

    I was having this same issue for weeks and suddenly today it just got worse. Wouldn't connect to itunes, wouldn't update apps, wouldn't backup, etc. for my ipod touch 4. I tried the iphoto ipod photo cache delete and it backed it up! I am a happy camper now. :D
  24. macrumors newbie

    Jan 4, 2012
    Most of the time iTunes doesnot work to create backup of iPhone data. It deliver error messages either in the beginning of backup process or in the middle of that. But if you want to create backup without any problem, simply then just use professional iPhone backup software.

    Get the cheap and affordable ( backup software for different purpose individually. get the software for complete backup, Music or SMS or Contact backup. :D

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