FTP 125 Data Connection Open vs 553 File Name Not Allowed
FTP 125 (Data Connection Open) is a 1xx Positive Preliminary response, while 553 (File Name Not Allowed) 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, 553 means that requested action not taken. File name not allowed. The file or directory name violates the server's naming rules or filesystem restrictions.
Description
The data connection is already open and the transfer is beginning. No need to open a new data connection.
When You See It
When the server reuses an existing data connection for a file transfer instead of opening a new one.
How to Fix
No fix needed — the transfer is starting immediately. Your client should begin reading or writing data on the existing connection.
Description
Requested action not taken. File name not allowed. The file or directory name violates the server's naming rules or filesystem restrictions.
When You See It
When you try to create or rename a file with characters the server's filesystem does not allow, such as special characters or reserved names.
How to Fix
Rename the file to use only allowed characters. Avoid special characters like ?, *, |, <, >, and leading/trailing spaces or dots.
Key Differences
125 is a 1xx Positive Preliminary response, while 553 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 553: Requested action not taken. File name not allowed. The file or directory name violates the server's naming rules or filesystem restrictions.
You encounter 125 when when the server reuses an existing data connection for a file transfer instead of opening a new one.
You encounter 553 when when you try to create or rename a file with characters the server's filesystem does not allow, such as special characters or reserved names.
When to Use Which
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 553 (File Name Not Allowed): Rename the file to use only allowed characters. Avoid special characters like ?, *, |, <, >, and leading/trailing spaces or dots.