Here is the list of some of the most common FTP codes:
100 - Codes that the requested action is being taken. Expect a reply before proceeding with a new command.
110 - Restart marker reply.
120 - Service ready in (n) minutes.
125 - Data connection already open, transfer starting.
150 - File status okay, about to open data connection.
200 - Codes the requested action has been successfully completed.
202 - Command not implemented
211 - System status, or system help reply.
212 - Directory status.
213 - File status.
214 - Help message.
215 - NAME system type. (NAME is an official system name from the list in the Assigned Numbers document.)
220 - Service ready for new user.
221 - Service closing control connection. (Logged out if appropriate.)
225 - Data connection open, no transfer in progress.
226 - Closing data connection. Requested file action successful (file transfer, abort, etc.).
227 - Entering Passive Mode
230 - User logged in, proceed.
250 - Requested file action okay, completed.
257 - "PATHNAME" created.
300 - Codes the command has been accepted, but the requested action is being held pending till receipt of further information.
331 - User name okay, need password.
332 - Need account for login.
350 - Requested file action pending further information.
400 - Codes the command was not accepted and the requested action did not take place. The error condition is temporary, however, and the action may be requested again.
421 - Service not available, closing control connection. (May be a reply to any command if the service knows that it must be shut down.)
425 - Can't open data connection.
426 - Connection closed, transfer aborted.
450 - Requested file action not taken. File unavailable (e.g., file busy).
451 - Requested action aborted, local error in processing.
452 - Requested action not taken. Insufficient storage space in system.
500 - Codes the command was not accepted and the requested action did not take place. Syntax error, command unrecognized. 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 - User not logged in.
532 - Need account for storing files.
550 - Requested action not taken. File unavailable (e.g., file not found, no access).
552 - Requested file action aborted, storage allocation exceeded
553 - Requested action not taken. Illegal file name.