title: Crystal Reports and .NET 4 - Could not load file or assembly (with useLegacyV2RuntimeActivationPolicy="false") crdb_adoplus.dll
body: <p>A little background - my application is currently built in .NET 3.5 but I would like to migrate it to .NET 4.0.  When I change all projects to point at .NET 4.0 my application runs fine until I try to open a Crystal Report.</p>
  
  <p>My error is as follows:</p>
  
  <pre><code>Could not load file or assembly 'file:///C:\Program Files (x86)\SAP BusinessObjects\Crystal Reports for .NET Framework 4.0\Common\SAP BusinessObjects Enterprise XI 4.0\win32_x86\dotnet1\crdb_adoplus.dll' or one of its dependencies. The system cannot find the file specified.
  </code></pre>
  
  <p>I've searched and there are quite a few answers to this question in the form of adding variations of the following to the app.config:</p>
  
  <pre><code>  &lt;startup useLegacyV2RuntimeActivationPolicy="true"&gt;
    &lt;supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/&gt;
    &lt;/startup&gt;
  </code></pre>
  
  <p>However, this solution does not work for me.  I use another assembly in my project (more specifically, Intuit's ProFile) which does not work once I set useLegacyV2RuntimeActivationPolicy="true".  I assume this is due to the fact some of their Tax Engines are pre v4 assemblies.</p>
  
  <p>So my question is how I proceed from here?  Leaving my application in .NET 3.5 is really only a temporary fix.</p>
  
  <p>Could I toggle useLegacyV2RuntimeActivationPolicy at runtime (i.e. set it to true before I load a Crystal Report) or is this a hack / even possible?  </p>
  
  <p>Is there a better way?</p>
  
  <p>Any insight would be greatly appreciated.</p>
  
  <p>Thanks,</p>