cp from shell (Terminal) or Finder: "Operation not supported" An odd issue here after an upgrade from High Sierra to Catalina.  When I try to copy files from an SMB network share in the Terminal (bash and zsh), I get:
$ cp /Volumes/share_name/path/file.ext  ~/Documents 
cp: /Volumes/share_name/path/file.ext: Operation not supported

When I try to copy the same file via Finder, I get &quot;The operation can't be completed because it isn't supported&quot;:

I've tried to execute this with sudo and I've tried to repair user permissions (user ID is501, so: sudo diskutil resetUserPermissions / 501) and the same results.
Important to note: Other systems with Catalina work just fine with the same SMB share.
It turned out that the problem was actually an existing /etc/nsmb.conf. When this was removed the SMB client behavior returned to normal in this regard. Within it, the previous user had defined:
[default]
signing_required=no
protocol_vers_map=1