I installed in a new workstation ArcGIS 10.4, VS 2012 and Vs 2015, ArcGIs SDK last available version.
I copied a web service that works fine in 10.2, VS 2012, and when I look for "Add ArcGIS reference" in Reference context menu, it is missing. When I compile the project it shows all Esri.ArcGIs libraries underlined and it fails. I have this problem in both VS 2012 and VS 2015 after I upgraded to ArcGIS 10.4.1.
This web service works fine as is in 10.2 VS 2012.
How to fix that?