the customer have been complaining that users of the site experience occasional downtime so we installed some monitoring software on the solution. This gave a possible source of the downtime.
This an error that happens periodically and we haven't been able to recreate it.
Error message
Stack trace
[NullReferenceException: Object reference not set to an instance of an object.]
at Dynamicweb.Frontend.NavigationProviders.GroupNavigationProvider.MakeGroupTree(GroupCollection groups, NavigationItem parentNode, Int32 thisLevel, Int32 maxLevel, Page productPage)
at Dynamicweb.Frontend.NavigationProviders.GroupNavigationProvider.MakeGroupTree(GroupCollection groups, NavigationItem parentNode, Int32 thisLevel, Int32 maxLevel, Page productPage)
at Dynamicweb.Frontend.NavigationProviders.GroupNavigationProvider.MakeGroupTree(Page page, NavigationItem parentNode)
at Dynamicweb.Frontend.NavigationProviders.GroupNavigationProvider.Process(NavigationItem node)
at Dynamicweb.Frontend.XmlNavigation.XML(Int32 ParentID, Int32 StartLevel, Int32 StopLevel, Expand expand, Int32 areaID)
at Dynamicweb.Frontend.XmlNavigation.GetNavigationHtml(Int32 ParentID, Int32 StartLevel, Int32 StopLevel, Expand ExpandMode, String NavigationName, String XsltPath, Int32 AreaID, Boolean SitemapMode, NameValueCollection settings, NameValueCollection attributes, IncludeMode mode)
at Dynamicweb.Frontend.XmlNavigation.GetNavigationHtml(NameValueCollection settings, NameValueCollection attributes)
at Dynamicweb.Frontend.XmlNavigation.GetNavigationHtml(DynamicElement d)
at Dynamicweb.Frontend.XmlNavigation.ParseNavigationTags(Template t, Layout l)
at Dynamicweb.Frontend.PageView.SetPageTemplateValues()
at Dynamicweb.Frontend.PageView.Output()
at Dynamicweb.Frontend.PageviewControl.ParseControls()
at System.Web.UI.Control.InitRecursive(Control namingContainer)
at System.Web.UI.Control.AddedControl(Control control, Int32 index)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
[HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown.]
at System.Web.UI.Page.HandleError(Exception e)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest()
at System.Web.UI.Page.ProcessRequest(HttpContext context)
at ASP.default_aspx.ProcessRequest(HttpContext context)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)