I've been confused by this for years, because I eventually realized that the error message is false. When I copy a file to one of my phones with cp -urv, the terminal says "operation not supported." But the thing is, the operation obviously is supported. It worked: the file was copied. Why would the system suggest that it can't copy the files (what "operation not supported" means to me) when it can and does copy the files?

Just an odd curiosity.

...oh. I just figured it out. The problem was my parameter to preserve the dates. The system can't do that. Oh, well.

Are you copying to a filesystem that doesn't support users and Unix-type file permissions like FAT? If so, it's "operation not supported" when trying to set the user and file permissions. When I save files to USB sticks (formatted with FAT) that I want to work with multiple OSs, I get that.