I downgraded a project from 4.5.1 to 3.5 (server compatibility) and then I got this warning:
Namespace or type specified in the project-level Imports 'System.Threading.Tasks' doesn't contain any public member or cannot be found. Make sure the namespace or the type is defined and contains at least one public member. Make sure the imported element name doesn't use any aliases.
The program still works fine, but I'd like to get rid of this error if possible.