I have an ASP.Net MVC application which works fine on IIS 6.0 / Windows Server 2003. When installed on IIS 7.5 / Windows Server 2008 (integrated mode), it works but when the application attempts to generate an URL, it runs into the following error: [NullReferenceException: Object reference not set to an instance of an object.] System.Web.HttpServerVarsCollection.Get(String name) +10960764 System.Web.Mvc.PathHelpers.GenerateClientUrlInternal(HttpContextBase httpContext, String contentPath) +345 System.Web.Mvc.PathHelpers.GenerateClientUrl(HttpContextBase httpContext, String contentPath) +80 System.Web.Mvc.UrlHelper.GenerateUrl(String routeName, String actionName, String controllerName, RouteValueDictionary routeValues, RouteCollection routeCollection, RequestContext requestContext, Boolean includeImplicitMvcValues) +256 System.Web.Mvc.UrlHelper.Action(String actionName, String controllerName, RouteValueDictionary routeValues) +36 It looks like IIS7 fails to return the server name. There should be a configuration to set, but I couldn't find anything like that. Do you have any idea to fix this issue ? Thanks,