I have created a Custom Server Control that renders the SiteMap as a pure UL for CSS styling. At run-time it renders properly but in VS2008 Design View VS shows this error: Error Rendering Control - menuMainAn unhandled exception has occurred. The provider 'AspNetXmlSiteMapProvider' specified for the defaultProvider does not exist in the providers collection. I have 'AspNetXmlSiteMapProvider' specified in web.config as per here : link text While I am happy that the code runs properly, the Designer error is bothersome if the underlying issue might cause the code to break in some circumstances so I need to understand what is going on... The code explicitly references the sitemap in the Render Method with : int level = 1; string ul = string.Format("<div class='{0}' id='{1}'>{2}</div>", CssClassName, this.ID.ToString(), EnumerateNodesRecursive(SiteMap.RootNode, level)); output.Write(ul); and the recursive method called referrences SiteMap.CurrentNode. Otherwise there are no explicit sitemap references in the code. Does anyone have any ideas why Deisgner is complaining?