The error below is more than likely a direct error from WinSCP trying to read the directory upon connection and it doesn't occur all the time. It has been noticed when connecting WinSCP to some DR's as the administrator you may or may not get the error:
Command 'ls -la '
failed with return code 1 and error message
ls: -la: No such file or directory.
If you get the above error click ok and proceed with the copy.
Finally, when uploading the file as administrator, it may reach 99% and show fail. But the code is actually auto-detecting any incoming upgrade package and convert that to /store/DRxxxx_payload.tgz. So it may take a little time to show up. System --show --upgradefile from ssh terminal should eventually display the new file.