Transfer large files

WTF, i loading my folder with site. BUT WINSCP CANNOT UPLOAD FILE TO SERVER. WHY?@@?
i have slow internet and i leave the updownload for the night. But in the morning I do not see the uploaded site. Only this ficken window where is writing "Copy failed to server"

Sorry, i love this program, but this error is too furious.

How can I solve this problem?

If you retry the upload, does it succeed or fail with the same error?