FTP 125 Data Connection Open vs 426 Connection Closed
FTP 125 (Data Connection Open) is a 1xx Positive Preliminary response, while 426 (Connection Closed) is a 4xx Transient 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, 426 means that connection closed; transfer aborted. The data connection was closed unexpectedly during a file transfer.
Mô tả
The data connection is already open and the transfer is beginning. No need to open a new data connection.
Khi bạn thấy mã này
When the server reuses an existing data connection for a file transfer instead of opening a new one.
Cách khắc phục
No fix needed — the transfer is starting immediately. Your client should begin reading or writing data on the existing connection.
Mô tả
Connection closed; transfer aborted. The data connection was closed unexpectedly during a file transfer.
Khi bạn thấy mã này
When a file transfer is interrupted due to a network timeout, client disconnect, or the data connection dropping mid-transfer.
Cách khắc phục
Retry the transfer. If it keeps failing, check network stability, increase timeout values, and verify there are no firewalls killing idle connections.
Sự khác biệt chính
125 is a 1xx Positive Preliminary response, while 426 is a 4xx Transient Negative response.
FTP 125: The data connection is already open and the transfer is beginning. No need to open a new data connection.
FTP 426: Connection closed; transfer aborted. The data connection was closed unexpectedly during a file transfer.
You encounter 125 when when the server reuses an existing data connection for a file transfer instead of opening a new one.
You encounter 426 when when a file transfer is interrupted due to a network timeout, client disconnect, or the data connection dropping mid-transfer.
Khi nào dùng cái nào
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 426 (Connection Closed): Retry the transfer. If it keeps failing, check network stability, increase timeout values, and verify there are no firewalls killing idle connections.