FTP 215 System Type vs 421 Service Not Available
FTP 215 (System Type) is a 2xx Positive Completion response, while 421 (Service Not Available) is a 4xx Transient Negative response. 215 indicates that the NAME system type, where NAME is an official system name from the list in the Assigned Numbers document. Reports the operating system of the server. In contrast, 421 means that service not available, closing control connection. The server is shutting down or has reached its connection limit and cannot serve this request.
説明
The NAME system type, where NAME is an official system name from the list in the Assigned Numbers document. Reports the operating system of the server.
このコードが表示される場合
After issuing the SYST command. The server reports its operating system type, commonly 'UNIX Type: L8' or 'Windows_NT'.
解決方法
No fix needed — use this information to adjust path separators and line endings for the server's OS type.
説明
Service not available, closing control connection. The server is shutting down or has reached its connection limit and cannot serve this request.
このコードが表示される場合
When the FTP server is overloaded, shutting down for maintenance, or has reached its maximum number of concurrent connections.
解決方法
Wait a few minutes and try reconnecting. If persistent, check if the server has a connection limit and whether your IP is being rate-limited.
主な違い
215 is a 2xx Positive Completion response, while 421 is a 4xx Transient Negative response.
FTP 215: The NAME system type, where NAME is an official system name from the list in the Assigned Numbers document. Reports the operating system of the server.
FTP 421: Service not available, closing control connection. The server is shutting down or has reached its connection limit and cannot serve this request.
You encounter 215 when after issuing the SYST command. The server reports its operating system type, commonly 'UNIX Type: L8' or 'Windows_NT'.
You encounter 421 when when the FTP server is overloaded, shutting down for maintenance, or has reached its maximum number of concurrent connections.
どちらをいつ使うか
For 215 (System Type): No fix needed — use this information to adjust path separators and line endings for the server's OS type. For 421 (Service Not Available): Wait a few minutes and try reconnecting. If persistent, check if the server has a connection limit and whether your IP is being rate-limited.