I've summarized some information in this new article:
This exception must have an inner exception that contains the real error. Without knowing that, we cannot help you. Though make sure you use the same version of WinSCP and WinSCP .NET assembly.
I'm having a similar issue. SSIS project / packages were created using VS2013, SSDT-BI for VS2013, WinSCP 5.7.5; deployed on Sql Server 2014. We've upgraded to VS2017, SSDT for VS2017, WinSCP 5.11.2; deploying SSIS project / packages to same server (Sql 2014). Had to make minor change(s) to project/packages, as target database was migrated to Sql 2016 (new server); managed to make packages run locally (in VS 2017), but deploying to SSIS server, the job / packages fail. Error message:
Exception has been thrown by the target of an invocation.