FTP 211 System Status vs 421 Service Not Available
FTP 211 (System Status) is a 2xx Positive Completion response, while 421 (Service Not Available) is a 4xx Transient Negative response. 211 indicates that system status or system help reply. The server provides information about its current status or available features. 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.
Mô tả
System status or system help reply. The server provides information about its current status or available features.
Khi bạn thấy mã này
After issuing the STAT command without arguments, the server returns its system status and supported features.
Cách khắc phục
No fix needed — this is an informational response. Use the information to understand the server's capabilities and current state.
Mô tả
Service not available, closing control connection. The server is shutting down or has reached its connection limit and cannot serve this request.
Khi bạn thấy mã này
When the FTP server is overloaded, shutting down for maintenance, or has reached its maximum number of concurrent connections.
Cách khắc phục
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.
Sự khác biệt chính
211 is a 2xx Positive Completion response, while 421 is a 4xx Transient Negative response.
FTP 211: System status or system help reply. The server provides information about its current status or available features.
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 211 when after issuing the STAT command without arguments, the server returns its system status and supported features.
You encounter 421 when when the FTP server is overloaded, shutting down for maintenance, or has reached its maximum number of concurrent connections.
Khi nào dùng cái nào
For 211 (System Status): No fix needed — this is an informational response. Use the information to understand the server's capabilities and current state. 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.