In function app added WinSCP as a reference and using WinSCP.exe for connecting to SFTP. This could indicate lack of write permissions to the log folder or problems starting WinSCP itself.

We need way more details. How exactly are you using the assembly? Can you post debug and session log files?

Current version of WinSCP is 5.21.6
When request is initiated it is throwing error

Failed to create target sftp client: WinSCP process terminated with exit code -1073741502 (C0000142).

So please suggest some appropriate solution for the above issue.