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.
الوصف
The data connection is already open and the transfer is beginning. No need to open a new data connection.
متى تراه
When the server reuses an existing data connection for a file transfer instead of opening a new one.
كيفية الإصلاح
No fix needed — the transfer is starting immediately. Your client should begin reading or writing data on the existing connection.
الوصف
Syntax error in parameters or arguments. The command was recognized but its arguments are invalid or malformed.
متى تراه
When you use a valid command but with wrong parameters, such as an invalid path format or incorrect argument count.
كيفية الإصلاح
Review the command's required argument format. Common issues include missing quotes around paths with spaces or invalid character encoding.
الفروق الرئيسية
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.
متى تستخدم أيًا منهما
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.