Errors backing up Photos.Sparsebundle I've been trying to backup / copy my Photos Library.sparsebundle and keep running into issues.

The original file is on a Drobo5N mount.I am trying to copy to an external SSD

The Sparsebundle is 168GB in size and the copy takes most of the night before failing at the last hurdle.

The initial error that I received, with copy reporting 164/168GB was

The operation can't be completed because you don't have persmission to access 'Photos Library.sparsebundle'

The file is not open in Photos. The Target drive was formatted APFS, encrypted and the source is DroboFS so doesn't support Mac OS permissions (owner listed as "unknown")

I tried to rsync the file last night and the copy failed with an error about not being able to set time on a file (sorry, didn't have chance to copy the error). Most of the files had copied according to the drive size but the sparse bundle was "unbundled"

I've reformatted the target drive as HFS+, journaled, encrypted and set a new copy going. 

Any ideas what is happening?
So I managed to get an answer from the Apple Community boards.

I reformatted the External SSD as HFS+, Journaled, encrypted rather than APFS, encrypted and the copy went through with no problems.

I will now be treating the SSD as the Primary and the Drobo as the Backup.