FTP server response codes are helpful for system administrators in charge of their company’s FTP server. Oftentimes, users might see these response codes listed in their favorite FTP client, such as FileZilla.

When troubleshooting a file transfer problem, it’s often helpful to identify the FTP response code that is being thrown around. It’s also important to ask what time of connection they’re using (ie FTP, SFTP or FTPS).

This guide will help you understand each element of the FTP server response code so you can get a better feel of what’s happening. It will also give you a full listing of each error code.

FTP Server Response Codes: The First Digit

The first digit in the FTP server code lets you know whether or not the that step was successful. They also tell you what you should expect next. For instance, a 100 level code tells you that the process has started and to expect another code shortly.

Range Purpose

Positive Preliminary Reply

The request is being initiated and you should expect another reply before proceeding with a new command. If a user sends another command before the reply completion the server-FTP process should queue the commands while this is in progress. This type of reply can indicate that the command was accepted and the user-process may now pay attention to the data connections, for implementations where simultaneous monitoring is difficult. The server-FTP process may send, at most, one 1xx reply per command.


Positive Completion Reply

The request was successful. A new request may now be sent.


Positive Intermediate Reply

The command was accepted but the request is being held in abeyance, pending the receipt of more information. The user should send another command with this information. This reply is used in command sequence groups.


Transient Negative Completion Reply

The command wasn’t accepted and the request didn’t occur, but the error condition is temporary and the action may be resent. The user should return to the beginning of the command sequence, if any. A rule of thumb in determining if this reply belongs to the 4xx (Temporary Negative) or the 5xx (Permanent Negative) category is that replies are 4xx if the commands can be repeated without any change in command form or in properties of the User or Server.


Permanent Negative Completion Reply

The command wasn’t accepted and the requested action didn’t occur. The User-process shouldn’t repeat the exact same request (in the same sequence). Some “permanent” error conditions can be fixed, so the human user may want to direct his User-process to reinitiate the command sequence by direct action (e.g., the user has changed his directory status.)


Protected Reply

The RFC 2228 introduced the concept of protected replies to increase security over the FTP communications. The 6xx replies are Base64 encoded protected messages that serves as responses to secure commands. When decoded, these replies fall into the above categories.

FTP Response Codes: The Second Digit

The second digit in the FTP server code lets you know what group or category the request belongs too. For instance, it tells you if it’s regarding connections or if it’s regarding authentication.

Range Purpose


These replies refer to syntax errors, syntactically correct commands that don’t fit any functional category, unimplemented or superfluous commands.



Replies to requests for information, like help or support.



Replies regarding the control and data connections.


Authentication and accounting

Replies for the login process and accounting procedures.

x4x Unspecified as of RFC 959.

File system

Indicates the status of the Server file system vis-a-vis the requested transfer or other file system action.

FTP Server Codes: The Third Digit

The third digit in the FTP serve code gives further explanation on what exactly is causing this code. Usually it’s the final piece of the puzzle.

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FTP Server Codes: List of Error Codes

Here is a full list of known FTP server error codes:

Code Explanation
100 Series The request has started, expect another reply before proceeding with a new command.
110 Restart marker replay. In this case, the text is exact and not left to the particular implementation; it must read: MARK yyyy = mmmm where yyyy is User-process data stream marker, and mmmm server’s equivalent marker (note the spaces between markers and “=”).
120 Service ready in xx minutes.
125 Data connection is already open and the transfer is starting.
150 File status is okay and about to open data connection.
200 Series The request was successfully completed.
202 Command was not implemented, superfluous at this site.
211 System status, or system help reply.
212 Directory status.
213 File status.
214 Help message. On how to use the server or the meaning of a particular non-standard command.
215 NAME system type. Where NAME is an official system name from the registry kept by IANA.
220 Service is ready for new user.
221 Service closing control connection.
225 Data connection is open and no transfer is in progress.
226 Closing the data connection. Requested file action successful (for example, file transfer or file abort).
227 Entering Passive Mode (h1, h2, h3, h4, p1, p2).
228 Entering Long Passive Mode (long address, port).
229 Entering Extended Passive Mode (|||port|).
230 User has logged in, proceed. Logged out if appropriate.
231 User has logged out and the service is terminated.
232 Logout command noted, will complete when the transfer done.
234 Specifies that the server accepts the authentication mechanism specified by the client, and the exchange of security data is complete. A higher level nonstandard code created by Microsoft.
250 Requested file action okay and completed.
257 “PATHNAME” created.
300 Series The command was accepted, but the request is on hold, pending receipt of further information.
331 User name okay, need password.
332 Need account for login.
350 Requested file action pending further information
400 Series The command wasn’t accepted and the requested action didn’t occur, but the error condition is temporary and the action may be requested again.
421 Service not available, closing control connection. This may be a reply to any command if the service knows it must shut down.
425 Can’t open data connection.
426 Connection closed; transfer aborted.
430 Invalid username or password.
434 Requested host unavailable.
450 Requested file action not taken.
451 Requested action aborted. Local error in processing.
452 Requested action not taken. Insufficient storage space in system.File unavailable (e.g., file busy).
500 Series Syntax error, command unrecognized and the request did not take place. This may include errors such as command line too long.
501 Syntax error in parameters or arguments.
502 Command not implemented.
503 Bad sequence of commands.
504 Command not implemented for that parameter.
530 Not logged in.
532 Need account for storing files.
550 Request not taken. File unavailable (e.g., file not found, no access).
551 Request aborted. Page type unknown.
552 Requested file action aborted. Exceeded storage allocation (for current directory or dataset).
553 Requested action not taken. File name not allowed.
600 Series Replies regarding confidentiality and integrity
631 Integrity protected reply.
632 Confidentiality and integrity protected reply.
633 Confidentiality protected reply.
10000 Series Common Winsock Error Codes
10054 Connection reset by peer. The connection was forcibly closed by the remote host.
10060 Cannot connect to remote server.
10061 Cannot connect to remote server. The connection is actively refused by the server.
10066 Directory not empty.
10068 Too many users, server is full.

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Sources: SmartFile’s I.T. Personnel, Wikipedia

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I'm the Digital Marketing Manager for SmartFile who loves content, email marketing and web analytics. As a child, I built awesome websites with animated starry night backgrounds and multi-colored font headers on AngelFire and GeoCities.

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