title: TFS Build error MSB4126 (solution configuration is invalid) how to fix
body: <p>I was working on migrating a website to a web project, I updated the project and everything is fine locally, I've switched to building the solution instead of the project.  But when building on the build server, I'm getting an error message </p>
  
  <blockquote>
    <p>c:\agent_work\10\s\mySolution.sln.metaproj(0,0): Error MSB4126: The
    specified solution configuration "Debug|AnyCPU" is invalid. Please
    specify a valid solution configuration using the Configuration and
    Platform properties (e.g. MSBuild.exe Solution.sln
    /p:Configuration=Debug /p:Platform="Any CPU") or leave those
    properties blank to use the default solution configuration.</p>
  </blockquote>
  
  <p>What is wrong and more importantly, what do I do to fix it?</p>