Solution :
If you are using the wrong user name or password then you will get the above error
[1] Access your control panel at https://www.yourdomain.com:8443 [ Example :https://www.servername:8443 ]
[2] Click on subscriptions.
[3] Click on subscription name which you want to change the FTP password
[4] Click on Website & Domains and click on " Web hosting Access "
[5] Change the FTP password.
[6] Click on ok.
Note : Give the FTP password very tough which consists of alphanumeric characters.