FTP 125 Data Connection Open vs 500 Syntax Error
FTP 125 (Data Connection Open) is a 1xx Positive Preliminary response, while 500 (Syntax Error) 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, 500 means that syntax error, command unrecognized. The server could not parse the command. This may also be sent when the command line is too long.
Descripción
The data connection is already open and the transfer is beginning. No need to open a new data connection.
Cuándo lo verás
When the server reuses an existing data connection for a file transfer instead of opening a new one.
Cómo solucionarlo
No fix needed — the transfer is starting immediately. Your client should begin reading or writing data on the existing connection.
Descripción
Syntax error, command unrecognized. The server could not parse the command. This may also be sent when the command line is too long.
Cuándo lo verás
When you send a malformed or misspelled command, or a command the server does not recognize at all.
Cómo solucionarlo
Check the command spelling and syntax. Use HELP to see the list of supported commands on this server.
Diferencias clave
125 is a 1xx Positive Preliminary response, while 500 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 500: Syntax error, command unrecognized. The server could not parse the command. This may also be sent when the command line is too long.
You encounter 125 when when the server reuses an existing data connection for a file transfer instead of opening a new one.
You encounter 500 when when you send a malformed or misspelled command, or a command the server does not recognize at all.
Cuándo usar cada uno
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 500 (Syntax Error): Check the command spelling and syntax. Use HELP to see the list of supported commands on this server.