WinSCP may not be compatible without your server.
But in any case, you should try to the latest version of WinSCP first. There have been some relevant improvements.
I'm using the .Net library PutFile() method to upload a file. Getting the following error:
Ascii transfer mode selected.
. 2017-03-30 15:51:07.025 Starting upload of \\Canton\data\Real Estate\ims\FTP TRANSFERS\bankfile.txt
> 2017-03-30 15:51:07.025 CWD /'FTSTRS02.'/FTSTRS02/
< 2017-03-30 15:51:07.181 500 User Exit denies Userid 'FTSTRS02' from using Command 'CWD'.
> 2017-03-30 15:51:07.181 CWD /'FTSTRS02.'/
< 2017-03-30 15:51:07.290 500 User Exit denies Userid 'FTSTRS02' from using Command 'CWD'.
> 2017-03-30 15:51:07.290 CWD /
< 2017-03-30 15:51:07.399 500 User Exit denies Userid 'FTSTRS02' from using Command 'CWD'.
. 2017-03-30 15:51:07.399 Copying files to remote side failed.
* 2017-03-30 15:51:07.399 (ExtException) **Copying files to remote side failed.**
* 2017-03-30 15:51:07.399 User Exit denies Userid 'FTSTRS02' from using Command 'CWD'.
What is the CWD command trying to do? It appears to be issued by WINSCP 3 times here.
WINSCP Version: 5.5.5, Windows 7 Enterprise