The application attempted to perform an operation not allowed by the security policy

I have a web site that allows clients to fill out a form (data stored on SQL Server), then click a button to save attachments which can be large so I plan to save them on the web server.

I start by creating a directory;

Directory.CreateDirectory(Server.MapPath("~\App_Data\Docs\" & idDoc))

(Yes - I am certain that idDoc has a valid value)

When I try to create a directory through code-behind I get "The application attempted to perform an operation not allowed by the security policy".

 

Thanks, Elshadriel - that got it working!

Thanks, Elshadriel - that got it working!