Yes, I mean .NET assembly. Kindly please add info about minimum required WinSCP version which work with .NET to the download page, to any place in which the info will be obvious, and also to https://winscp.net/eng/docs/message_library_timeout_waiting_to_respond as it is possibly a cause of problem for some users (as it was in our case -- it took me an hour to dig through sources of WinSCP 4.2.9, then 5.5.5, then .NET connector to see why it doesn't work). It also causes false reports, and you need to waste your time responding to them etc. etc. Thanks in advance! :)
The only reason you might get the "Timeout waiting for WinSCP to respond" error due to a version is that you are using a different version of the assembly and WinSCP (what is never recommended) and you explicitly disabled the version check using
Session.DisableVersionCheck. Quoting note at this property:
Note, even if you set this property, you need to use the assembly with compatible WinSCP executable only. Otherwise the behavior is unpredictable. In general, it is not recommended to use this. In neither case you will be able to use the assembly with WinSCP 5.0.4 or older.