looks like this problem is still not solved in the last version 3.0 build 159. as it was reported before https://winscp.net/forum/viewtopic.php?p=910
now program does not crash but insted acts quite strange.
to produce this error you need a linux box with groups. make one file owner a person A and group A and file permissions rw-rw-r--
now as a user B that exists in group A you should be able to overwrite this file since it has u,g - rw permissions even if the owner is user A from the same A group with you (user B), right?
when you try to overwrite the file the error message appears
scp: /usr/local/apache/htdocs/public_html/images/style.css: set mode: Operation not permitted
you can click whatever button you like but you will get only one message
Unexpected directory listing line "
after that the program does not crash but shows clear window with no directory listing at all.
if you click refresh it shows another message
Command "pwd ; echo "WinSCP: this is end-of-file:$?"" failed with invalid output "".
and nothing happends again...
who cares anyway