 <p>Late answer , but maybe someone is struggling with this... here is what I found:</p> <p><a href="http://stackoverflow.com/questions/3652331/asp-net-application-throwing-unable-to-find-assembly-error-for-nhibernate">Similar error on this question, which leads to some options</a>.</p> <p>Looks like the real error is hidden from you. </p> <p>1) You need to either use <a href="http://www.microsoft.com/en-us/download/details.aspx?id=40336" rel="nofollow">IIS Debug tool</a></p> <p>2) <a href="http://unhandledexception.codeplex.com/sourcecontrol/latest" rel="nofollow">Or build and use a module</a> to get the details.</p>