Host is not communicating for more than 15 seconds v. 5.1

got this error when uploading file the server.

it takes me a few hours to figure this out. I read this page online
https://winscp.net/eng/docs/message_host_is_not_communicating but it didn't help. It turned out that I did have enough space for file. It is a 24Gig file.

winscp should check for diskspace or warn of not enough space instead this generic error message.

Your server should report an error, instead of just stopping responding in the first place.