FTP-ssl error: Unsupported record version Unknown 48.48

[desilvam]

what does this error mean?
Unsupported record version Unknown 48.48

server requires client/server certificates to be used.
Connected to server:
Command : AUTH SSL (also tried AUTH TLS and implicit ssl)
Response : 234 Proceed with negotiation
Command : USER ...
Response : 331 Please specify the password
Command : PASS ***
Unsupported record version Unknown 48.48

[vglass]

This error can be because the server is not providing an SSL encrypted stream after username and password are sent.

[desilvam]

The server was CoreFtp LE. It turned out to be an issue on the server end. thanks.