Mac photos to WD Easystore: Unknown error (3

I receive a pop up window with "Unknown error (3)" when attempting to transfer photos from my iMac to a WD Easystore external hard drive.I tried reformatting the devise from APFS, Mac OS Extended, ExFAT and nothing is working. I tried to convert some of the photos to jpeg and Im stilling getting the error code. The devise is brand new so I know the connection should be good. Im running out of ideas.

iPhone 12 Pro

Posted on Jan 11, 2026 8:56 AM

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Question marked as Top-ranking reply

Posted on Jan 19, 2026 7:02 AM

I'm still not quite sure I see it. What macOS are you using. What iOS are you using?


It sounds like you are not using the Mac Photos app in the transfer-- is that right? Are you using Image Capture to transfer pictures to a Finder folder? And then the error occurs when you try to drag files from a Mac Finder folder to the external drive-- is that right? There are so many ways to "transfer" things, that it helps if you an be specific.


Have you transferred other files to the drive-- does that work OK? Is this only about picture files? It's beginning to sound like the iMac's USB port might be a problem. Have you tried other ports?


Have you used Virus hunters or Mac Cleaners on the iMac?


As long as you're not using the drive on Windows, then APFS is the best choice of format. If it's a pretty old Mac, and you're running an old OS, Mac OS Extended (Journaled) is good. It's best if it's not encrypted, and Case Sensitive format can't be used.


You should check Permissions on the drive. You can open the Info Panel for the drive by selecting it and using command-i. An APFS format has an "Ignore Permissions" box that needs to be checked, for instance.


Have you used the Disk Utility app to do a First Aid check on the drive?


With all that, try these things to help narrow things down:

  • Restart the computer (of course)
  • Re-start in Safe Mode. This bypasses certain potentially disruptive processes, and it often helps. Safe Mode is different for different computers, so see this: 

           Start up your Mac in safe mode - Apple Support 

  • Make a new user and see if the same problem recurs with it.  This is a bit harder, because a new user can't access a different user's stuff. You would need to temporarily move your Library out of your own user's Pictures folder up to the general "Users" folder. 


Let us know what happens…


4 replies
Question marked as Top-ranking reply

Jan 19, 2026 7:02 AM in response to asf85

I'm still not quite sure I see it. What macOS are you using. What iOS are you using?


It sounds like you are not using the Mac Photos app in the transfer-- is that right? Are you using Image Capture to transfer pictures to a Finder folder? And then the error occurs when you try to drag files from a Mac Finder folder to the external drive-- is that right? There are so many ways to "transfer" things, that it helps if you an be specific.


Have you transferred other files to the drive-- does that work OK? Is this only about picture files? It's beginning to sound like the iMac's USB port might be a problem. Have you tried other ports?


Have you used Virus hunters or Mac Cleaners on the iMac?


As long as you're not using the drive on Windows, then APFS is the best choice of format. If it's a pretty old Mac, and you're running an old OS, Mac OS Extended (Journaled) is good. It's best if it's not encrypted, and Case Sensitive format can't be used.


You should check Permissions on the drive. You can open the Info Panel for the drive by selecting it and using command-i. An APFS format has an "Ignore Permissions" box that needs to be checked, for instance.


Have you used the Disk Utility app to do a First Aid check on the drive?


With all that, try these things to help narrow things down:

  • Restart the computer (of course)
  • Re-start in Safe Mode. This bypasses certain potentially disruptive processes, and it often helps. Safe Mode is different for different computers, so see this: 

           Start up your Mac in safe mode - Apple Support 

  • Make a new user and see if the same problem recurs with it.  This is a bit harder, because a new user can't access a different user's stuff. You would need to temporarily move your Library out of your own user's Pictures folder up to the general "Users" folder. 


Let us know what happens…


Jan 11, 2026 11:41 AM in response to asf85

This is a mechanical spinning drive, is that right? Since an iPhone 12 uses a lightning port, how are you connecting it to your drive? What iOS are you using? Exactly what buttons are you pushing? I think I would select pictures, choose Share>Save to Files and navigate to the drive. Do you see the drive in the Files app?


If you use a Mac, you should use a Mac formatted drive to get the best results. If you use Windows, then ExFAT will do.



Jan 18, 2026 3:13 PM in response to Richard.Taylor

I'm connecting the phone directly to the iMac and transferring the photos to the computer. And then I'm selecting the photos from the file that the photo is saved. Some of the photos are no longer on the phone, but even most recent photos that are still on the phone won't transfer over to the hard drive. And yes this is a mechanical spinning drive, but I have also tried using a usb thumb drive and have had the same answer.

Mac photos to WD Easystore: Unknown error (3

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