This error comes in variants:
- WinSCP process terminated with exit code 3 and output "", without creating a log file.
- WinSCP process terminated with exit code 3 and output "", without responding.
This error indicates that WinSCP process started by WinSCP .NET assembly did not correctly start. Make sure your process has permissions to access WinSCP executable and to execute processes. See also related fix for for frequent use of the .NET assembly.