Would this article help?
https://winscp.net/eng/docs/faq_scheduler
https://winscp.net/eng/docs/faq_scheduler
Before posting, please read how to report bug or request support effectively.
Bug reports without an attached log file are usually useless.
open mysession
Searching for host...
Host does not exist
winscp.StartInfo.Arguments = "/log=" + logname;
ERROR: Cannot create Log file.
ERROR: The server's host key was not found in the cache. You have no guarantee that the server is the computer you think it is.
The server's rsa2 key fingerprint is:
ssh-rsa 1024 94:45:5e:00:18:d0:a3:34:c1:0e:db:48:17:b0:a6:f5
If you trust this host, press Yes. To connect without adding host key to the cache, press No. To abandon the connection press Cancel.