Attempting to copy to the disk Macintosh HD failed. An unknown error occurred (-54).

== Error -54 ==

From an OS9 reference, error -54 is a software lock on a file or a permissions error. (Although there is no formal list of OSX error code some of the old codes still apply to OSX .)

First, try simply restarting your computer.

Try quitting iTunes, then deleting the .xml (not .itl !) version of the library file in the iTunes folder (iTunes will generate a new one).

iTunes Library cannot be saved (Error -54) - https://discussions.apple.com/thread/1912814 - various things to try.

Unknown error (-54) while syncing ipod - https://discussions.apple.com/thread/1082953 - problem was locked files

Why does iTunes keep showing a -54 error when I sync my iPad? - https://discussions.apple.com/thread/3727114

Error -54 possibly related to Touch Copy - https://discussions.apple.com/thread/3727114 - cleared by deleting preferences on iPad.

iTunes: Missing folder or incorrect permissions may prevent authorization - http://support.apple.com/kb/ts1277

Troubleshooting permissions issues in Mac OS X - http://support.apple.com/kb/HT2963

I repaired disc permissions, did a SAFE reboot, shutdown and restarted my computer normally. I shut down then restarted the iPhone 6c, plugged it back into the computer and it seems to have cleared up the problem.

This has developed in the last day for me. Tried all the suggestions but none helped. All software is up to date (as of 10/15), though I haven't moved to El Capitan yet. However, I only received this message when I do a USB sync (don't use wi-fi sync) to my iPhone 5s, everything is fine when I USB sync my iPad Air. Any ideas here?

exactly the same for me! My iPhone 6 plus is on the latest version but I do NOT want the stupid El Captain OS because all of my 3rd party DJ software and music production companies warned me that they were not compatible yet!

<Edited By Host>

I seemed to have solved my issue, though I'm not exactly sure what caused it.

I have 2 users set up on my iMac, one for personal use and the other for work. I only sync my iPhone and iPad with my personal user account. The trouble for me may have begun when I mistakenly attached my iPhone via USB when running my work user. It tried to sync but I immediatly stopped that. Apparently that was enough to switch some ownership or permissions. I only noticed it when some events failed to appear in my calendar (I don't use iCloud). Both the Sync Contacts and Sync Calendar functions in iTunes had been turned off. When I turned them on iTunes said there were 2 users and did I want to merge. I said yes and that seemed to fix the problem and so far I'm not seeing any issues in either my contacts or calendars

I think it started since last iTunes update, was having the same issue but only on iPhone (not the case for iPad), tried to restart everything.. as a last resort I tried hard restart with holding both buttons at once for few secs and no more error with -54... but what I noticed iTunes is not syncing apps directly from devices anymore. They throwed this step away?

Problem Solved!!!!!

Thank you, thank you thank you.

Going into the iTunes folder on my mac and deleting the .xml file worked.

Deleting xml file helped me too, thank you!

Thanks msg-

That worked for me, although with El Capitan I couldn't "repair disk permissions" as such, but I carried the "first aid" offered in Disk Utility, I tried so many other suggestions, but nothing worked until I followed your suggestion to boot in safe mode and restart the iPhone as well...✅

Had this on my phone 6 plus does not happen on my iPads, iPhone 5 or iPhone 4 did a reinstall on iPhone 6 about a month ago and it synced OK, problem came back again yesterday decided to reinstall iTunes and El Capitan updates that did not work, I also tried resetting just network settings on iPhone 6 and seems to have worked, not 100% certain it was this or just happened to sort itself out this but if someone else tries this if they have the same problem and see if it works ✅

I had the same problem and tried all the above and I found a different solution because none of the other suggestions fixed it for me, but they helped me look in the right area.

First start by quitting iTunes.

If you look in your home folder (the one with the house icon and your name on it), then the "Music" folder and then inside that will be another folder called "iTunes" you will find a file called "iTunes Music Library.xml". If you type cmd-I for Info and look at the section of the pop up screen that shows the "Sharing & Permissions", you may see a user with the Name "fetching..." and the computer looks like it's trying to retrieve some name (from the network? from iCloud? who knows?!). I then clicked the - button (in the +- pair of buttons in the lowest left hand corner) to remove that user and then the problem went away! Go back into iTunes and retry the sync. It worked for me. No more "error -54"! 🙂

Alex

Unlocking the phone before syncing solved it for me!

Similar issue. Just fixed it for PC windows 10. After trying all the steps as described above, no luck.

Then realized not signing in to iTunes account. After signing in, backing up completed. Hope this helps.

I also experienced the same problem (-54 error) where iTunes wouldn't complete the sync between the iPhone 6 Plus and my iMac. I tried deauthorise/authorise on the iMac. Tried setting File Sharing permissions to Read and Write on the iMac. Restarted the iMac. None of that worked. What did though was a simple restart of the iPhone 6 Plus. And now it syncs like a charm. Thank you for bringing to my notice that big problems often have the simplest of solutions!

I spent hours going back and forth with an AppleCare supervisor creating new/different iTunes libraries and nothing seemed to work. I also tried every fix on this thread, but the only solution that worked for me was unlocking my IPhone 6s before syncing.