FTP 150 File Status OK vs 503 Bad Sequence
FTP 150 (File Status OK) is a 1xx Positive Preliminary response, while 503 (Bad Sequence) is a 5xx Permanent Negative response. 150 indicates that the file status is okay and the server is about to open the data connection for the transfer. This is the normal precursor to a file transfer. In contrast, 503 means that bad sequence of commands. The command is valid but was sent in the wrong order relative to other commands.
Description
The file status is okay and the server is about to open the data connection for the transfer. This is the normal precursor to a file transfer.
When You See It
Right before a file download or upload begins, confirming the file is accessible and the data channel is being opened.
How to Fix
No fix needed — this means the transfer is about to start. If the transfer stalls after this reply, check firewall rules blocking the data connection.
Description
Bad sequence of commands. The command is valid but was sent in the wrong order relative to other commands.
When You See It
When you skip a required step, like sending PASS before USER, or RNTO without first sending RNFR.
How to Fix
Follow the correct command sequence. Common sequences: USER then PASS for login, RNFR then RNTO for rename, PASV then RETR for transfer.
Key Differences
150 is a 1xx Positive Preliminary response, while 503 is a 5xx Permanent Negative response.
FTP 150: The file status is okay and the server is about to open the data connection for the transfer. This is the normal precursor to a file transfer.
FTP 503: Bad sequence of commands. The command is valid but was sent in the wrong order relative to other commands.
You encounter 150 when right before a file download or upload begins, confirming the file is accessible and the data channel is being opened.
You encounter 503 when when you skip a required step, like sending PASS before USER, or RNTO without first sending RNFR.
When to Use Which
For 150 (File Status OK): No fix needed — this means the transfer is about to start. If the transfer stalls after this reply, check firewall rules blocking the data connection. For 503 (Bad Sequence): Follow the correct command sequence. Common sequences: USER then PASS for login, RNFR then RNTO for rename, PASV then RETR for transfer.