FTP 214 Help Message vs 421 Service Not Available
FTP 214 (Help Message) is a 2xx Positive Completion response, while 421 (Service Not Available) is a 4xx Transient Negative response. 214 indicates that help message. The server provides information about its implementation status, including a list of recognized commands or help for a specific command. 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.
描述
Help message. The server provides information about its implementation status, including a list of recognized commands or help for a specific command.
何时出现
After issuing the HELP command. The server returns a list of supported commands or detailed usage for a specific command.
如何修复
No fix needed — this is an informational response. Use it to discover which commands the server supports.
描述
Service not available, closing control connection. The server is shutting down or has reached its connection limit and cannot serve this request.
何时出现
When the FTP server is overloaded, shutting down for maintenance, or has reached its maximum number of concurrent connections.
如何修复
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.
主要区别
214 is a 2xx Positive Completion response, while 421 is a 4xx Transient Negative response.
FTP 214: Help message. The server provides information about its implementation status, including a list of recognized commands or help for a specific command.
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 214 when after issuing the HELP command. The server returns a list of supported commands or detailed usage for a specific command.
You encounter 421 when when the FTP server is overloaded, shutting down for maintenance, or has reached its maximum number of concurrent connections.
何时使用哪个
For 214 (Help Message): No fix needed — this is an informational response. Use it to discover which commands the server supports. 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.