How to Enable SSH Password Authentication
Some server providers, such as Amazon EC2 and Google Compute Engine, disable SSH password authentication by default. That is, you can only log in over SSH using public key authentication.
SFTP is a protocol that runs over SSH, so this means SFTP using passwords will not work by default when SSH password authentication is disabled.
To enable SSH password authentication, you must SSH in as root to edit this file:
Then, change the line
After making that change, restart the SSH service by running the following command as root:
sudo service ssh restart