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501 FTP response code

A 501 response code may be sent in response to any command that requires or supports the optional use of a parameter or argument. It is a permanent negative response, which means the client is discouraged from sending the exact command and parameter(s) again since the server will respond with the same response code.

First published date

10/25/2018 7:30 PM

Last published date

10/25/2018 7:30 PM

Overview

This article provides information on 501 FTP response code.

Product section

Serv-U Managed File Transfer & Serv-U FTP Server

Resolution

A 501 response code may be sent in response to any command that requires or supports the optional use of a parameter or argument. It is a permanent negative response, which means the client is discouraged from sending the exact command and parameter(s) again since the server will respond with the same response code. It differs from the 500 response code in that the server recognizes the command present but is unable to take the requested action due to a syntax error in the parameter(s) present with the command. Sending the same command to the server with a corrected parameter may result in a different response code.

Example response 

501 Syntax error in parameters or argument.

Possible commands 

A 501 reply code may be sent in response to any command requiring or supporting the use of a parameter or argument.