The connection to the FTP server is protected by the TLS security mechanism. The server FTP.DATA file contains the statement SECURE_LOGIN VERIFY_USER. The USER command that was received has a username that does not match the name found in the certificate sent from the client during the authentication handshake.
The USER command is rejected. FTP continues.
Log in using the username that matches the name that is passed in the client certificate.
If username match is not necessary, change the SECURE_LOGIN statement to have a value of either REQUIRED or OPTIONAL.