FTP 125 Data Connection Open vs 502 Command Not Implemented
FTP 125 (Data Connection Open) is a 1xx Positive Preliminary response, while 502 (Command Not Implemented) is a 5xx Permanent Negative response. 125 indicates that the data connection is already open and the transfer is beginning. No need to open a new data connection. In contrast, 502 means that command not implemented. The server recognizes the command but does not support it in its current configuration.
Descrição
The data connection is already open and the transfer is beginning. No need to open a new data connection.
Quando você o vê
When the server reuses an existing data connection for a file transfer instead of opening a new one.
Como corrigir
No fix needed — the transfer is starting immediately. Your client should begin reading or writing data on the existing connection.
Descrição
Command not implemented. The server recognizes the command but does not support it in its current configuration.
Quando você o vê
When you use a valid FTP command that this particular server has not implemented, such as SITE or SMNT.
Como corrigir
Use an alternative command or approach. Check the server's FEAT response or HELP output to see which commands are actually supported.
Diferenças principais
125 is a 1xx Positive Preliminary response, while 502 is a 5xx Permanent Negative response.
FTP 125: The data connection is already open and the transfer is beginning. No need to open a new data connection.
FTP 502: Command not implemented. The server recognizes the command but does not support it in its current configuration.
You encounter 125 when when the server reuses an existing data connection for a file transfer instead of opening a new one.
You encounter 502 when when you use a valid FTP command that this particular server has not implemented, such as SITE or SMNT.
Quando usar qual
For 125 (Data Connection Open): No fix needed — the transfer is starting immediately. Your client should begin reading or writing data on the existing connection. For 502 (Command Not Implemented): Use an alternative command or approach. Check the server's FEAT response or HELP output to see which commands are actually supported.