Issue with adding new machines to existing catalog. Following message is displayed:
Error Id: XDDS:6BDAEC45  "Object reference not set to an instance of an object"            

The exception might look like the following example:

Exception:

System.NullReferenceException Object reference not set to an instance of an object.
       at Citrix.Console.ProvisioningSchemes.UI.Pages.CatalogSummaryHelper.AddMcsSummary(SummaryBoxViewModel summaryBox)
       at Citrix.Console.ProvisioningSchemes.UI.Pages.CatalogSummaryHelper.PopulateSummaryBox(SummaryBoxViewModel summaryBox, Boolean clear)
       at Citrix.Console.ProvisioningSchemes.UI.Dialogs.AddMachinesWizardViewModel.<.ctor>b__6(Object s, EventArgs e)
       at Citrix.Console.CommonControls.SummaryBoxControl.SummaryBoxViewModel.UpdateSummary()
       at Citrix.Console.Shared.UI.Pages.SummaryPageViewModel.LoadPageData()
       at Citrix.Console.CommonControls.Wizard.PageBaseViewModel.LoadPageDataInternal()
       at Citrix.Console.CommonControls.ViewModelBase.<>c__DisplayClass1.<Invoke>b__0()
       at Citrix.Console.CommonControls.ViewModelBase.InvokeUntimed(Action action)
       at Citrix.Console.CommonControls.PropertyChangedSupport.PropertyChangedListener.propertyChanged(Object sender, PropertyChangedEventArgs e)
       at Citrix.Console.CommonControls.PropertyChangedSupport.ListenerNode.System.Windows.IWeakEventListener.ReceiveWeakEvent(Type managerType, Object sender, EventArgs e)
       at System.Windows.WeakEventManager.DeliverEventToList(Object sender, EventArgs args, ListenerList list)
       at System.ComponentModel.PropertyChangedEventManager.OnPropertyChanged(Object sender, PropertyChangedEventArgs args)

Complete the following steps:

1. Run Get-AcctidentityPool to identify the missing values from each catalog’s identity pool.

2. Run Set-AcctIdentityPool to add the missing values reported by preceding commands.
   Example:
   Set-AcctIdentityPool -IdentityPoolName <"Identity Pool Name" -NamingScheme <Naming Scheme> -Domain <DNS Suffix> -OU <”OU=OU path”> -Namingschemetype <Naming Scheme>

Problem Cause

Error might occur when some of the identity pool info is missing example domain, naming scheme,OU.

Get-AcctIdentityPool - Citrix Virtual Apps and Desktops 2009 SDK Documentation