I have been having trouble for a couple of months doing a full office backup of a specific folder on the server. This folder has 30,000+ files in it and I am trying to copy it to an external hard drive. After copying about half of the files I receive an error 0x80070052 unable to create file or directory. I thought it was a problem with the files on the server, but another backup drive I have attached to the server does not have this problem. I tried copying the files from that backup drive and encountered the same error.
I remembered the FAT limit of files in the root folder so I thought maybe there is a file limit in any folder. I checked my external drive and it was formatted FAT32 so I reformatted it to NTFS and tried again. Not only did the backup work this time, but the speed increased about threefold! Afterward I did a little research and there is a limit of 65,536 directory entries in FAT32 drive folders; each file and subdirectory can use a few to several entries depending on things like long file / folder names. So like me you can run into this problem even if you don’t have 60,000 files in a folder.
Therefore, if you are going to backup folders with thousands of files and don’t need to access an external hard drive from Mac OS or Linux, format the drive NTFS. You may save yourself some headaches.