502 FTP Reply Code - KB Article #1527Related Articles --
502 Command not implemented.
A 502 reply code may be sent in response to any FTP command the server does not support. It is a permanent negative reply, which means the client is discouraged from sending the command again since the server will respond with the same reply code. The original FTP specification dictates a minimum implementation for all FTP servers with a list of required commands. Because of this, a 502 reply code should not be sent in response to a required command.
A 502 reply code may be sent in response to any FTP command the server does not support.