NullReferenceException in MvcSiteMapProvider at production - asp.net-mvc-3

Question

The problem is I regularly get the error at the production site (ASP.NET MVC 3) but can't reproduce this error locally.
The text of exception is:
ExceptionType: System.NullReferenceException
Message: Object reference not set to an instance of an object.
StackTrace:
at System.Collections.Specialized.NameObjectCollectionBase.BaseGetAllKeys()
at System.Collections.Specialized.NameValueCollection.get_AllKeys()
at MvcSiteMapProvider.MvcSiteMapNode.get_MetaAttributes()
at MvcSiteMapProvider.Web.Html.SiteMapNodeModelMapper.MapToSiteMapNodeModel(SiteMapNode node, MvcSiteMapNode mvcNode, IDictionary`2 sourceMetadata)
at MvcSiteMapProvider.Web.Html.SiteMapPathHelper.BuildModel(MvcSiteMapHtmlHelper helper, SiteMapNode startingNode)
at MvcSiteMapProvider.Web.Html.SiteMapPathHelper.SiteMapPath(MvcSiteMapHtmlHelper helper, String templateName)
at ASP._Page_Views_Shared__LoggedInLayout_cshtml.Execute() in c:\Solution\Sites\Project2Site\Views\Shared\_LoggedInLayout.cshtml:line 86
at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
at System.Web.WebPages.WebPageBase.Write(HelperResult result)
at System.Web.WebPages.WebPageBase.RenderSurrounding(String partialViewName, Action`1 body)
at System.Web.WebPages.WebPageBase.PopContext()
at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context)
at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)
I have no such errors locally. Here is where I invoke MvcSiteMap().SiteMapPath() method:
May be somebody had the same problem before. If so please share your solution.
Thanks in advance.

Answer 1

This won't answer your question directly, but may help you on your path to debugging the issue, seeing as it happens only in production and not in dev/debug.
Consider replacing your line:
#Html.MvcSiteMap().SiteMapPath()
With something like:
#SafeBreadCrumb()
#helper SafeBreadCrumb() {
MvcHtmlString output;
try
{
output = Html.MvcSiteMap().SiteMapPath();
}
catch (Exception e)
{
output = new MvcHtmlString(e.Message);
}
<text>#output</text>
}
Feels a little dirty, but it's easier than grabbing the source of MvcSiteMapProvider and sticking in some logging! If it happened in debug, you wouldn't need to try this. Plus it's just a view change, so won't need a recompile.