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.
คำอธิบาย
The data connection is already open and the transfer is beginning. No need to open a new data connection.
เมื่อคุณพบเห็น
When the server reuses an existing data connection for a file transfer instead of opening a new one.
วิธีแก้ไข
No fix needed — the transfer is starting immediately. Your client should begin reading or writing data on the existing connection.
คำอธิบาย
Connection closed; transfer aborted. The data connection was closed unexpectedly during a file transfer.
เมื่อคุณพบเห็น
When a file transfer is interrupted due to a network timeout, client disconnect, or the data connection dropping mid-transfer.
วิธีแก้ไข
Retry the transfer. If it keeps failing, check network stability, increase timeout values, and verify there are no firewalls killing idle connections.
ความแตกต่างหลัก
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.
ควรใช้อันไหนเมื่อไร
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.