FTP 125 Data Connection Open vs 501 Syntax Error in Arguments
FTP 125 (Data Connection Open) is a 1xx Positive Preliminary response, while 501 (Syntax Error in Arguments) 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, 501 means that syntax error in parameters or arguments. The command was recognized but its arguments are invalid or malformed.
Beschreibung
The data connection is already open and the transfer is beginning. No need to open a new data connection.
Wann Sie es sehen
When the server reuses an existing data connection for a file transfer instead of opening a new one.
Wie man es behebt
No fix needed — the transfer is starting immediately. Your client should begin reading or writing data on the existing connection.
Beschreibung
Syntax error in parameters or arguments. The command was recognized but its arguments are invalid or malformed.
Wann Sie es sehen
When you use a valid command but with wrong parameters, such as an invalid path format or incorrect argument count.
Wie man es behebt
Review the command's required argument format. Common issues include missing quotes around paths with spaces or invalid character encoding.
Wesentliche Unterschiede
125 is a 1xx Positive Preliminary response, while 501 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 501: Syntax error in parameters or arguments. The command was recognized but its arguments are invalid or malformed.
You encounter 125 when when the server reuses an existing data connection for a file transfer instead of opening a new one.
You encounter 501 when when you use a valid command but with wrong parameters, such as an invalid path format or incorrect argument count.
Wann welchen verwenden
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 501 (Syntax Error in Arguments): Review the command's required argument format. Common issues include missing quotes around paths with spaces or invalid character encoding.