This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded
<p>I'm getting this error when trying to start a <strong>.net 4</strong>  <strong>windows service</strong>.
I tried a few things I found when I googled the problem:</p>

<p>I checked that all projects that being referred from my project have, in their<br>
  app.config, the lines:</p>

<pre><code>&lt;startup&gt;
 &lt;supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/&gt;
&lt;/startup&gt;
</code></pre>

<ul>
<li>I verified that I have .Net 4 Framework installed on my <strong>server 2008R2 machine</strong>.</li>
<li>I did the repair of .Net 4 installer and restarted the server.</li>
<li>I set the Startup object to my service.</li>
</ul>

<p>All projects complied with x64.</p>

<p>I'm out of ideas... help anybody?</p>
