title: VS 2012 - Project failed to build because of missing Toolset
body: <p>I am unable to compile/build anything within Visual Studio C++ 2012 because I am getting an error that states either I have an inappropriate ToolsVersion or that the ToolSet is missing. </p>
  
  <p>Here is the error in the console: </p>
  
  <blockquote>
    <p>Project file contains ToolsVersion="12.0". <strong>This toolset may be unknown
    or missing</strong>, 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="4.0". </p>
    
    <p>1>C:\Program Files
    (x86)\MSBuild\Microsoft.Cpp\v4.0\V110\Microsoft.Cpp.Platform.targets(44,5):
    error MSB8020: The builds tools for v120 (Platform Toolset = 'v120')
    cannot be found. To build using the v120 build tools, either click the
    Project menu or right-click the solution, and then select "Update VC++
    Projects...". <strong>Install v120 to build using the v120 build tools</strong>.</p>
  </blockquote>
  
  <p>I have installed Microsoft SDK. This may be relevant also - I downgraded from 2013 VSRC to 2012 MSVC recently but I made a clean uninstallation. </p>