WinSCP: General failure

WinSCP is a very nice tool for managing your server content form desktop OS. Meantime it sometimes can provide you very confusing error reports. For example, look at this:

General failure (server should provide error description).
Error code: 4
Error message from server:
Failure Request code: 14 

And who knows what's wrong?! Quick googling show that issue is caused by 100% full drive, so all you need is just clean up some space. And this confusing message is gone :)

References:
http://winscp.net/forum/viewtopic.php?t=1668