I just experienced the same problem with a Buffalo NAS - Error -50.
Upon looking at tthe folders that would not copy, I found they all contained a folder named “.AppleDouble” - from the terminal I used the ‘find’ command with ‘rm -rf’ on the results; now all the folders from which I’ve removed the “.AppleDouble” folder copy correctly, and show up with the proper icon. Before the removal, they all showed with a generic icon for the appropriate application. I’m sure there are better arguments to ‘find’ and ‘rm’ than I used, and I will look at that further.
I’m connecting to the NAS with AFP. I haven’t tried connecting with SMB yet, but will check that out, and research further details. Something creates .AppleDouble, and something objects to its presence.
Also, it would be nice if someone could suggest a solution that doesn’t use the terminal. Spotlight might help, but doesn’t offer some of the options of the classic Find File function.
