If you see error -54 when you sync with your computer
If your content doesn't sync, consolidate your iTunes Library files and check for issues with third-party security software.
When you try to sync your iPhone, iPad, or iPod touch with your computer, you might see an alert message that says:
"The iPhone [device name] cannot be synced. An unknown error occurred (-54)."
This can happen if a file on your computer or iOS or iPadOS device is locked. Click OK to continue the sync.
If your content doesn't sync, here's what to do:
Restart your computer and your iOS or iPadOS device.
If you're using iTunes on macOS Mojave or earlier or on a PC, make sure that you have the latest version of iTunes and the latest software updates for your device.
If you still see the issue, try the steps below.
Consolidate the media files in your computer
The media files in the Music app or iTunes library might be stored in several locations. Try consolidating your files into one library.
Check for issues with third-party security software
Some third-party software, including security software, can interfere with the sync process between your computer and your device. Change your security software's setup and see if it fixes the issue.
Sync a small amount of content
Sync only a small amount of content at a time. Add more content until you see the error again. By doing this, you'll identify the content that causes the issue.
Delete and re-download content
If the issue happens with content from the iTunes Store, delete and then redownload the apps and delete and then redownload music. Or, download the apps and download music directly to your iPhone, iPad, or iPod touch.
Delete and re-import content
If the content isn't from the iTunes Store, delete and then re-import it from the original source.
Remove PDF files from the sync process
This issue might happen when you try to transfer iTunes apps purchases or transfer iTunes music purchases from your iOS or iPadOS device to your computer. This might also happen when you try to sync with Apple Books, because it uses the same process. If so, there might be a problem with a PDF file saved to the Books app on your iOS device.
To fix the issue, use the Share option in the Books app on your device to email the PDF to yourself. This saves a copy of the PDF in your email account and shares it with the email address you choose, which can be accessed from your computer. Then, remove the PDF file from your device.
