The call goes like this (WPF):

REST0.Program.Connect();

Console application added to project

 using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace REST0 { public class Program { static void Main(string[] args) { } public static void Connect() { } } }

Build errors

A warning icon is highlighted in the links:

enter image description here

But this is empty in the list of errors

    2 answers 2

    Regarding the icon, this is not Error (Error), but Warning (Warning). To see it, just open the window with a list of errors and click the warning display tab here:

    enter image description here

    And as you have already correctly noted - just a version mismatch. The solution is simple: go to the project properties, go to the Application tab (In Russified VS, the tab name will be Application ) and find the Target Framework property there

    enter image description here

    For both projects, set the same version of the framework and the warning will disappear. After that, the project will start. I wanted to write a comment, but the answer is too general - I decided to write a more detailed version so that it was useful for others.

      The version of the framework did not match in the projects.