FTP 120 Service Ready Soon vs 421 Service Not Available
FTP 120 (Service Ready Soon) is a 1xx Positive Preliminary response, while 421 (Service Not Available) is a 4xx Transient Negative response. 120 indicates that the service will be ready in a certain number of minutes. The server is not yet available but expects to be shortly. 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
The service will be ready in a certain number of minutes. The server is not yet available but expects to be shortly.
何时出现
When connecting to an FTP server that is starting up or temporarily busy with maintenance tasks.
如何修复
Wait the indicated number of minutes and try connecting again. If the server never becomes ready, contact the server administrator.
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
120 is a 1xx Positive Preliminary response, while 421 is a 4xx Transient Negative response.
FTP 120: The service will be ready in a certain number of minutes. The server is not yet available but expects to be shortly.
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 120 when when connecting to an FTP server that is starting up or temporarily busy with maintenance tasks.
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 120 (Service Ready Soon): Wait the indicated number of minutes and try connecting again. If the server never becomes ready, contact the server administrator. 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.