What previous version? 3.8? Do you mean that you type that full command (including the /upload parameter) into address box of IE? If that ever worked, it was definitelly not intended :-)

:) Stfp used to work with old version. After the new verion got released last week i uninstalled old version and installed new version and was trying to execute sftp from Internet explorer window. Nothing is happening.
sftp://user:pwd@host /upload C:/test.txt

with previous version it used to open winscp and copy the file to remote server with couple of confirm windows.

with new version it is not even opening winscp. by reading the documentation i went into preferences and registered sftp. but still it don't work.