I'm attempting to copy an 84 Gigabyte photo library from an external Case-sensitive Journaled HFS+ disk to a newly formatted case-insensitive APFS SSD. The external disk is in an external drive bay connected via USB.
The operation takes a few hours, at which point I'm greeted with the error message
You can’t copy this file because its name is the same as other items on the destination volume, and that volume doesn’t distinguish between upper- and lowercase letters in filenames.
There is no duplicate file on the drive.
Is the file name being cached somehow because of the file size? Is it something in the package contents? The file integrity is fine - I can open it as a photos library from the bay. I thought I could open it as a referenced file and use the Photo's Consolidate option to simply get around the issue, but "Show referenced file" and "consolidate" are both greyed out in the file menu.
Can I use rsync or some other method to copy the file or are there actual case-sensitivity issues in there I need to address? It's my wife's entire photo collection, so I'm proceeding with extreme caution, and would greatly appreciate guidance.