I had the same problem with asp.net mvc 4 and Rotativa. Adding a binding redirect for System.Web.Mvc in my web.config solve the problem for me.
<runtime>
<dependentAssembly>
<assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
</dependentAssembly>
</assemblyBinding>
</runtime>