title: Could not load file or assembly 'System.Runtime, Version=4.2.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
body: <p>I got the project from colleague and got this error when building project:</p>
  
  <blockquote>
    <p>Could not load file or assembly 'System.Runtime, Version=4.2.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.        </p>
  </blockquote>
  
  <p>I guess this dll is in .NET Framework Dll Folder: <code>C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework</code>, but after searching, I find many dll of other version, but I didn't find any <code>System.Runtime.dll</code> is <code>4.2.1.0</code>.</p>
  
  <p>Here's another <a href="https://stackoverflow.com/questions/53402798/system-runtime-version-4-2-1-0-publickeytoken-b03f5f7f11d50a3a-has-a-higher-ve">similar question</a> but no answer to it.</p>
  
  <p>Is <code>System.Runtime.dll 4.2.1.0</code> really exists in .NET Framework?</p>