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I am trying to move my Photo Library from my Macbook pro to an external hard drive (MyCloud). I keep getting an error message. "The Finder can’t complete the operation because some data in “Photos Library” can’t be read or written. (Error code -36)". I made sure to click the "lock" to unlock it and it says I have "Read and Write" privileges for both my Mac and the cloud.
MacBook
When moving a Photo Library to an external drive, you want to make sure it's using an Apple file system such as APFS or HFS+. This is a choice made when you first prepare the external drive for use on your Mac. If it is not in one for these two formats (which can be confirmed using Disk Utility) then you'd need to reformat it but that erases everything on the drive. So, you'd want to make a backup copy of everything to a different drive before doing this. And then move that all back after using Disk Utility to erase it and reformat it as an APFS or HFS+ drive. As a quick note, APFS is the newer format and is optimized for SSDs but it also lacks a breadth of utilities for fixing problems so some still prefer HFS+ (also known as Mac OS Extended format).
You will also want to set your external drive to ignore ownership so you don't run into permissions issues on your drive. This can be done by clicking on your external drive in Finder and then closing Get Info from the File menu. Expand the Sharing & Permissions section at the bottom and check the box to ignore ownership.
After verifying the above to eliminate them as the cause of your problem, you may be experiencing a damaged photo library. Try using the library repair tool to fix that. It's best if you have a backup either to iCloud, Time Machine or the like. Then hold down Command-Option when starting Photos and you'll be prompted to run the repair.
If it still won't copy over after all of this, you may have a drive problem or other corruption in the photo library. In this case you essentially will need to try to recover the photos from inside the library. I won't go into details yet on that as you've got some other things to try first.
When moving a Photo Library to an external drive, you want to make sure it's using an Apple file system such as APFS or HFS+. This is a choice made when you first prepare the external drive for use on your Mac. If it is not in one for these two formats (which can be confirmed using Disk Utility) then you'd need to reformat it but that erases everything on the drive. So, you'd want to make a backup copy of everything to a different drive before doing this. And then move that all back after using Disk Utility to erase it and reformat it as an APFS or HFS+ drive. As a quick note, APFS is the newer format and is optimized for SSDs but it also lacks a breadth of utilities for fixing problems so some still prefer HFS+ (also known as Mac OS Extended format).
You will also want to set your external drive to ignore ownership so you don't run into permissions issues on your drive. This can be done by clicking on your external drive in Finder and then closing Get Info from the File menu. Expand the Sharing & Permissions section at the bottom and check the box to ignore ownership.
After verifying the above to eliminate them as the cause of your problem, you may be experiencing a damaged photo library. Try using the library repair tool to fix that. It's best if you have a backup either to iCloud, Time Machine or the like. Then hold down Command-Option when starting Photos and you'll be prompted to run the repair.
If it still won't copy over after all of this, you may have a drive problem or other corruption in the photo library. In this case you essentially will need to try to recover the photos from inside the library. I won't go into details yet on that as you've got some other things to try first.
Error when trying to move Photo Library to external drive. "Some data in Photos Library can't be read or written."
