title: VS 2015 Toolset may be unknown or missing
body: <p>I try to publish project to my file directory.</p>
  
  <p>I take a this message. But do not shown any error. Error list is empyty.</p>
  
  <blockquote>
    <p>2> Building with tools version "14.0".</p>
    
    <p>2> Project file contains ToolsVersion="12.0". This toolset may be
    unknown or missing, in which case you may be able to resolve this by
    installing the appropriate version of MSBuild, or the build may have
    been forced to a particular ToolsVersion for policy reasons. Treating
    the project as if it had ToolsVersion="14.0". For more information,
    please see <a href="http://go.microsoft.com/fwlink/?LinkId=293424" rel="noreferrer">http://go.microsoft.com/fwlink/?LinkId=293424</a>. 2> Target
    "ValidateMSBuildToolsVersion" skipped. Previously built
    unsuccessfully. 2>Done building project "project_name.csproj" – FAILED. 2>
    ========== Build: 1 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========
    ========== Publish: 0 succeeded, 1 failed, 0 skipped ==========</p>
  </blockquote>