ftp - Getting 503 Bad Sequence after entering username -

i have ftp server on device, user name: xyz. before performing ftp, have done nmap check if port 21 open , is. device accepting connections on port 21. ftp device , enter user name , server responds 503 bad commands.

i searched lot, not answer. please me in regard.

here tcp stream:

220 ftp server connected.

user xyz

503 bad sequence of commands

thanks, ravi.