FTP 202 Command Superfluous vs 551 Page Type Unknown
FTP 202 (Command Superfluous) is a 2xx Positive Completion response, while 551 (Page Type Unknown) is a 5xx Permanent Negative response. 202 indicates that the command is not implemented but is recognized as superfluous. The server acknowledges the command but it has no effect. In contrast, 551 means that requested action aborted: page type unknown. The server does not recognize the requested page structure or format.
Mô tả
The command is not implemented but is recognized as superfluous. The server acknowledges the command but it has no effect.
Khi bạn thấy mã này
When you send a command the server recognizes but considers unnecessary, such as ALLO on a server that does not require pre-allocation.
Cách khắc phục
No fix needed — the server is telling you the command is not necessary. You can safely ignore this response and continue.
Mô tả
Requested action aborted: page type unknown. The server does not recognize the requested page structure or format.
Khi bạn thấy mã này
When attempting a transfer with a page structure type the server does not support. This is extremely rare in modern FTP usage.
Cách khắc phục
Switch to stream transfer mode (MODE S) and file structure (STRU F), which are universally supported by all FTP servers.
Sự khác biệt chính
202 is a 2xx Positive Completion response, while 551 is a 5xx Permanent Negative response.
FTP 202: The command is not implemented but is recognized as superfluous. The server acknowledges the command but it has no effect.
FTP 551: Requested action aborted: page type unknown. The server does not recognize the requested page structure or format.
You encounter 202 when when you send a command the server recognizes but considers unnecessary, such as ALLO on a server that does not require pre-allocation.
You encounter 551 when when attempting a transfer with a page structure type the server does not support. This is extremely rare in modern FTP usage.
Khi nào dùng cái nào
For 202 (Command Superfluous): No fix needed — the server is telling you the command is not necessary. You can safely ignore this response and continue. For 551 (Page Type Unknown): Switch to stream transfer mode (MODE S) and file structure (STRU F), which are universally supported by all FTP servers.