the error you are seeing is not the best indicator of what is happening. Your code for an (normal) FTP session won’t work directly for a FTPS (FTP SLL) session. You have to modify your code to handle the certificate in the FTPS session.
You should take a look at the Xceed FileSystem Snippet Explorer, which can be found under Start -> Programs -> Xceed Components -> .NET Components -> Class Librairies -> Xceed FTP for .NET 4.1 -> Xceed FileSystem Snippet Explorer
Once you have the Snippet Explorer open, examine the section 4.1.3. Securely, using SLL/TLS
This should put you back on track pretty quickly. The code is self-explanatory and can be executed (and modified) right from the Snippet Explorer.
Applies to Xceed FTP for .NET. Imported from legacy forums. Posted by Ghislain (had 1812 views)