FTP 220 Service Ready vs 503 Bad Sequence
FTP 220 (Service Ready) is a 2xx Positive Completion response, while 503 (Bad Sequence) is a 5xx Permanent Negative response. 220 indicates that service ready for new user. This is the greeting message sent by the FTP server when a client first connects. 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
Service ready for new user. This is the greeting message sent by the FTP server when a client first connects.
When You See It
Immediately upon connecting to an FTP server. This is the welcome banner confirming the server is accepting connections.
How to Fix
No fix needed — the server is ready. Proceed with USER and PASS commands to authenticate.
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
220 is a 2xx Positive Completion response, while 503 is a 5xx Permanent Negative response.
FTP 220: Service ready for new user. This is the greeting message sent by the FTP server when a client first connects.
FTP 503: Bad sequence of commands. The command is valid but was sent in the wrong order relative to other commands.
You encounter 220 when immediately upon connecting to an FTP server. This is the welcome banner confirming the server is accepting connections.
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 220 (Service Ready): No fix needed — the server is ready. Proceed with USER and PASS commands to authenticate. 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.