Error ERROR Validation Error BC31424: Type 'System.Net.NetworkCredential' in assembly 'b6b727f1-47d9-4b4f-a171-53df40ce3258, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' has been forwarded to assembly 'System.Net.Primitives, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. Either a reference to 'System.Net.Primitives, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' is missing from your project or the type 'System.Net.NetworkCredential' is missing from assembly 'System.Net.Primitives, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.
This error basically occurs due to version issues so try updating the packages to the latest version and keep the runtime rule as lowest applicable version and the issue will be resolved.