Mac Studio: Error-Code 50 prevents copying files to external drive

I'm a photographer with two huge external backup drives. I run a year old Mac Studio with 96 GB Ram, M3 Ultra processor.


My Main drive crashed and I discovered some corruption on my backup Rocstor 22TB. I immediately ordered a new external drive and wanted to backup all my files on the new drive I named Backup 2 (26TB).



I quickly copied a 12 TB library file successfully. FYI the file named "65" use to be named My Lightroom and contained all my Lightroom files. Don't know how it was renamed to "65" that's the scary part and the reason for quick new Backup 2 (26TB) drive.



Then tried to copy the rest my data and files probably 3-4 TB and selected the file folders selected copy and when I went to the new Backup 2 drive and was unable to select "paste" and received an Error-Code 50 message.


I have been unable to transfer any more files. Did several restarts, ran the Disk Utility app, did a First Aid scan of the drive - no problems found. I did notice the Rocstor 22 TB HD listed the "Owners" as "Disabled" not sure if this is part of the corruption problem but I'm unable to change this condition.



Please advise how can I resolve the Code 50 error and finish copying files to the new Backup 2 drive?


Is the "Owner --- Disabled" part of the problem? If so how can I fix that?


Mac Studio, macOS 26.6

Posted on Oct 8, 2026 2:18 PM

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14 replies

Oct 13, 2026 9:00 AM in response to rwdepalma

rwdepalma wrote:
https://discussions.apple.com/content/attachment/658d809e-08b4-405b-96de-0101e6bd2601
I cleaned out the downloads and several other miscellaneous files on the desktop. I now have 129 GB of space on my internal solid state 1 TB HD (I should have bought a bigger HD).

No you do not have 129GB of space.....it is noted as "Available" which on macOS is not synonymous with Free. You may have 125GB of Free storage space that can be used immediately. Ignore the very misleading "Available" storage value shown everywhere in macOS. The only important storage value is the Free space value which is only shown correctly in Disk Utility.



After several restarts my Disk Utility is no longer displaying anything - just keeps loading. I still can't see my external drive with all my photo files. Now I can't even Mount it. Very very nervous.

Are these "backup" drives actually bootable macOS external drives? You do have to be very careful here if that is the case or you can really mess up your file/folder permissions especially if the macOS user accounts on them do not align perfectly with the UserIDs of your main boot drive.


If you are going to mix an external boot drive with also being a data drive, then you should at the very least create a new APFS volume on it to store files you want to access from various boot drives. And make sure to enable "Ignore Ownership" on that APFS volume. Better yet, have a dedicated external drive for the data with a dedicated external boot drive.



Also, when running First Aid....ignore the summary result as it may not be telling you the truth. Even if the First Aid summary says everything is "Ok", click "Show Details" and scroll through the report to see if any unfixed errors or warnings are listed. If there are any, then run First Aid again until they are gone. If after several scans the errors/warnings remain, then they cannot be repaired. Make sure to run First Aid on the hidden Container. You may need to click "View" within Disk Utility and select "Show All Devices" before the hidden Container & physical drives appear on the left pane of Disk Utility.

Oct 9, 2026 8:04 AM in response to rwdepalma

The most obvious place to look for a bit more space is in the Downloads folder, because everything there came from the Internet, and the vast majority can be re-downloaded if/when needed again.


Focus on copying this files.

Restart your Mac, and do not automatically start all your usual apps. In fact, actively QUIT ones you are not using in this moment (not just close windows, which leaves them running in the background). That will reduce required swap file space.

copy smaller groups of files, so that the auto-generated lists are smaller, and will not get clobbered by low space on the boot drive.



Oct 9, 2026 10:28 AM in response to Grant Bennet-Alder


I cleaned out the downloads and several other miscellaneous files on the desktop. I now have 129 GB of space on my internal solid state 1 TB HD (I should have bought a bigger HD).


After several restarts my Disk Utility is no longer displaying anything - just keeps loading. I still can't see my external drive with all my photo files. Now I can't even Mount it. Very very nervous.

Mac Studio: Error-Code 50 prevents copying files to external drive

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