I have "Googled" for information on this code but have not been able to find out exactly what could be happening that produces these error messages. Any help would be appreciated. :)
Error code 4 means "General failure". This is result of terrible bug reporting in OpenSSH server (do you use OpenSSH, right?). I can hardly help you, blame them. Generally the reason is "insufficient permissions".
Also important is what is the main error message (what you have posted are just additonal info to some error message). The upload may as well succeed, the error could happend during some post-upload task. Read F.A.Q.